Drumagog converts everything to 32-bit float when you create GOGs, and so I'm assuming the factory GOGs are 32-bit as well. apTrigga uses your samples exactly as they are. This may have something to do with the sonic differences between the two.
What kind of multi-sampling are you referring to? Dynamic, Positional, etc? There are very good instructions in the apTrigga PDF.
Obviously Drumagog has a much greater multi-sample capability, but it doesn't convince me. Anyway, the only time I would find that many multi-samples desirable is if I was trying to completely replace a snare drum or a snare roll, but I never do that! I use samples for reinforcement, with the exception of rock/metal where the kick is usually completely replaced. It depends on how good the drummer's foot is! I'll replace toms in metal too, but it sounds better to use samples for reinforcement and mix in some of the original sound to "humanize" it with the player's actual touch, instead of trying to replace the entire thing with multi-samples the way Drumagog does. Ugh, I get irritated just thinking about all the time I spent trying to get Drumagog to do what it claims to be able to do. I thought it was broken, buggy, I thought it was just me, but no! Reinforcement is really where it's at, not replacement. Just because we can use samples and we now have tools like this that make our lives easier doesn't mean you should abandon the art of micing a drumkit. Killer drum sounds take time, samples or not. I think it's pretty easy to get a decent & usable drum sound for metal using a pair of cheap SDC's, spot-mics on each drum, and some good samples.