Hi Rasher, I know this thread is super old, but I thought I'd share my outcome with messing around with the fins on my Bing Dharma. I'd been basically trying a whole bunch of fins on my Dharma with fcs boxes. I tried the PC 5, the SA 4, the AM 2s, and the funny thing was that I found that the rear fins made more of a difference than the front fins. In my opinion, the Dharma has so little rocker it's a hard board to surf top to bottom, so issues like fin release don't matter as much since I surf the board very laterally.
At any rate, I have the SA 2s mounted on the front pretty much all the time, as I prefer the drive from the wide base of the fins then depending on wave size and type I would swap out the rear fins between the gxq or a bigger set of rear fins that i have. I found in smaller or mushier waves, the gxq rears worked better as the board seemed easier to get into a wave (less draggy somehow) and went faster down the line. On bigger waves or waves with better shape, the bigger rears give more hold.
Just my thoughts.