bitflipper
I never joined the "where's SD3" chorus because I can't imagine what SD2 might be missing.
About the only thing on my wishlist is the ability to customize the mixer window so I don't have to scroll past all those unused channels, but I wouldn't pay a hundred bucks for that. More effects, maybe? Nah, I always route instruments to separate audio tracks, so I've got all the effects I need. More canned MIDI? Nope, never use what's already there. A sizeable UI would be nice, I guess.
You're right it's not really missing anything essential. Although a few new goodies might be welcome. A better UI, an auto drum fill feature, a tap 2 find search (like in EZ Drummer 2), and maybe a quicker load time? Otherwise, I find that SD2 does exactly what I need it to do and sounds great doing it.
But that's still not going to stop me from buying SD3...just because it's there and it's new.