tapir: What about modern past-komi matches? Are there any systems? (e.g. normal, with komi, white without komi, white with reverse komi, 2 handicap with komi etc.) - Seems like the jumps are bigger like this directly from even to sth similar to josen.
Herman: I think that in the current day and age, jubango matches are very rare among professionals. They take a long time, while there has been a consistent trend toward shorter time limits. The komi system does allow finer tuning of the handicaps, and for example the Ing rules specify that 2 points is an appropriate difference per grade. So under Ing komi rules:
|Rank difference||Amount of komi|
|same rank||8 komi for white|
|1 rank (pro)||6 komi for white|
|2 ranks||4 komi for white|
|3 ranks||2 komi for white|
|4 ranks||no komi|
|5 ranks||2 komi for black|
|6 ranks||4 komi for black|
|7 ranks||6 komi for black|
|8 ranks||8 komi for black (or 2 stones + 8 komi for white)|
Note: The above table is wrong! The 2 points komi mentioned by Ing are 2 zi, and are hence equivalent to 4 komi under the Japanese system we are familiar with. So it should be something like:
|Rank difference||Amount of komi|
|same rank||8 komi for white|
|1 rank (pro)||4 komi for white|
|2 ranks||no komi|
|3 ranks||4 komi for black|
|4 ranks||2 handicap, 8 komi for white (or just 8 komi for black)|
|5 ranks||2 handicap, 4 komi for white|
|6 ranks||2 handicap, no komi|
|7 ranks||2 handicap, 4 komi for black|
|8 ranks||2 handicap, 8 komi for black (or 3 stones + 8 komi for white)|
tapir: With sen ai sen both players will play white/black with other systems even the only slightly stronger player will always play white. Since we use a similar system in our go club... I'm interested in alternative handicap types, increased komi or sth. similar
Herman: Well, you might look at some of the pages under Club Ladder. The Dutch class system, for example, does sort of what you describe above (even, black with no komi, two stones with komi, two stones without komi, etc). The Point Ranking Scheme At Tokyo Go clubs is more fine-grained. Both can very well be used for a match, shifting the handicap after some number of losses/wins.
tapir: Yes. Our system looks quite similar to the dutch class system in a way... however all these modern systems let you play only one colour against players of only slightly different skill. Isn't sen ai sen the better handicap?
Herman: Well, in the above system, sen-ai-sen is used for one pro rank difference, ie two players that are about 1/3 of a stone apart in strenght. From 2 ranks (2/3 of a stone) onward, the weaker player always takes black. It is of course possible to make a system where the weaker player gets white with an increased komi, but I think that beyond a certain point (say a 2 stone rank difference), that doesn't work very well anymore. But at small differences, it can work quite well. Also, I think many players enjoy playing even games against someone even if that opponent is much stronger. You might also consider dagger go, or the option for the weaker player to switch sides after a certain number of moves (say 50 or 100).
The following part was moved from jubango handicaps.
John F. Bob, have you actually seen ni-ni-ni and san-san-san? I don't think I've ever come across any term other than the standard jou-ni and jou-san.
Since uchikomi matches were predominantly classical affairs, it should be noted that older terms were in use: e.g. sen-tagai-sen instead of sen-ai-sen, and there are variants: e.g. senzenni for sennisen, and sen-futatsu for sen-ni. 
Apart from series of three there were series of two, but I haven't come across a series of four. The number of games used to determine a shift in handicap is not always four. History students will recall this was one of the big issues of the one of the first ever challenge matches, where precedent differed from what was proposed.
Bob: No, John, I haven't seen these terms. I made them up to indicate briefly the fact that the handicap didn't change but I agree jou-ni and jou-san are correct (like jou-sen). If I'm guilty of perpetuating an incorrect usage, I apologize.
HolIgor: Recently, Rui Naiwei played a jubango with Pak Chi-eun. But they changed the handicap after two wins in a row. The match was interesting as, first, Rui forced Pak to the handicap and then, Pak fought back and forced Rui to the handicap. They ended even.
Bob: The system I described above is the one used in the Go Seigen matches and the one used classically, but the terms of change in playing conditions could be negotiated by the sponsors before the match. The games between the amateur and pro Honinbo have a handicap that changes every game, for example.
 John F. My own method in GoGoD, where I introduced a private sgf token OH, for Old Handicap, is to use BBW (or BWB in modern games) and to put brackets round whichever game it was in the series of three e.g. B(W)B.
SWeasley? Excuse me, suppose Mr. A play a Jubango with Mr. B. Mr. A scored four games lead and thus force Mr. B to sen-ai-sen. What if Mr. B win next game? Will the handicap change back to Tagai-sen? Thanks for answering.
Bob McGuigan: No, usually all changes of handicap required getting a four game lead. Calculating the lead begins anew after a change of handicap so Mr. B will have to build a four game lead to get back to tagai-sen, and the soonest that could happen would be if B wins the next three games in a row. In a ten-game match with terms as in the Go Seigen matches it would be difficult to recover once you were "beaten down".
Tokumoto FYI, I recently added an article, Points Rating System, describing a method used by Go clubs and salons in Japan.
Each step is about one-third of a stone
|Rank difference||Handicap||komi equivalent||pure komi|
|same rank||tagai-sen||6 komi for white||6 komi for white|
|1 rank (pro)||sen-ai-sen||4 komi for white||4 komi for white|
|2 ranks||jo-sen||0 komi for white||0 komi for white|
|3 ranks||sen-ni-sen||2 stones + 8 komi for white||4 komi for black|
|3.5 ranks||sen-ni||2 stones + 6 komi for white||6 komi for black|
|4 ranks||ni-sen-ni||2 stones + 4 komi for white||8 komi for black|
|5 ranks||jo-ni||2 stones + 0 komi for white||12 komi for black|
|6 ranks||ni-san-ni||3 stones + 8 komi for white||16 komi for black|
|6.5 ranks||san-ni||3 stones + 6 komi for white||18 komi for black|
|7 ranks||san-ni-san||3 stones + 4 komi for white||20 komi for black|
|8 ranks||jo-san||3 stones + 0 komi for white||24 komi for black|
Alternatively, if each step is half-stone:
|Rank difference||Handicap||komi equivalent|
|same rank||tagai-sen||6 komi for white|
|1 rank||jo-sen||0 komi for white|
|2 ranks||sen-ni||2 stones + 6 komi for white|
|3 ranks||jo-ni||2 stones + 0 komi for white|
|4 ranks||ni-san||3 stones + 6 komi for white|
|5 ranks||jo-san||3 stones + 0 komi for white|
|6 ranks||san-yon||4 stones + 6 komi for white|
|7 ranks||jo-yon||4 stones + 0 komi for white|
|8 ranks||yon-go||5 stones + 6 komi for white|
|9 ranks||jo-go||5 stones + 0 komi for white|