I'll give you another newbie's viewpoint; BCD. I had rented jacket-styles for a couple of different dives, but once I tried a back-inflate and then spent time diving in it, I found that my trim and bouyance improved bit-by-bit with each dive. Obviously some of that is just gaining experience. However, the ability to use intergrated weights with the same setup (or tweek as necessary), the ability to clip my regs, lights, etc.. in the same spot each time was one less set of things I needed to concentrate on during the dive. There is enough stuff for us newbies to process that if you can reduce the variation associated with switching BCDs each dive, I think it will allow you to concentrate on all of the other stuff.