I fly cabrinhas, and I've had pretty much every kite in the range. I fly the larger sizes (11M+) on the A setting, and smaller sizes on B. The 9m i fly on A or B depending on how I'm feeling. I find that on the A setting smaller kites are a bit faster turning than I like, and its easy to loose track of them in the air when doing tricks - on the B it seems much easier to know where the kite is in the air without looking at it, and gives more confidence doing bigger front/ backrolls etc.
Anyway - it's so easy to swap around - go out on your next session and try the other setting and see how you like it! I stuck on A setting for about 2 years without trying the B setting, but finally when I decided to give it a go on the 7m chaos I much preferred it.