So far, I've left the factory presets alone in the first, what is it, 384 slots? I've been going through the new ones again, one by one, and if I like one a lot, I'll save an edited copy in the last bank with my other personal presets. I pretty much always need to edit at least a little, for levels if nothing else.
I like being able to go back through the originals, checking for gems I might have missed, and seeing if I lost my way on some, so my copy is worse than how it came.
I'm not currently using any commercial presets, though I have some. There are a couple of highly regarded packs from the usual suspects that I might investigate, which of course would make things a lot more crowded.
I'm resisting wanting more preset capacity, since my IR adventures have confirmed what I already knew: Stuff expands to fill All The Space, no matter how much there is.