Rapid counting (Japanese style): Let O_i be the number of occupied and U_i the number of unoccupied intersections in the territory of player i (1: Black, 2: White). Let R_1 be the number of black and R_2 the number of white removed stones. Let P_i be the number of moves that player i has passed. White must move last, by an additional pass if necessary. Since the players move alternately, O_1+R_1+P_1 = O_2+R_2+P_2, therefore the difference of interest is (O_1+U_1)-(O_2+U_2) = (U_1-R_1-P_1)-(U_2-R_2-P_2), which can be counted rapidly by appropriate use of material (keep prisoners, give a stone for each pass, fill territory with prisoners, count unoccupied intersections). Idea taken from AGA rules.
Flower: I think this is a rather uneccesary addition here. While it is true that Equivalence Scoring/Counting can be used as a substitute for most Area 2 type rulesets It would be better to add a direct link to Equivalence Counting (which is in dire need of a WME :-/) A proof as to why it would be identical to area scoring would better fit on the Equivalence Counting page itself.(it adds too much unecessary info here) Furthermore R.Jasiek's proof of Equivalence counting is clearer and more detailed :) (see Equivalence Proof here: http://home.snafu.de/jasiek/int.html#EquivalenceProof)
Flower: Btw. thanks for your contribution anyways :) Once the Equivalence Counting/Scoring page is in better shape a link might be in order :D