A quick check in Delicious Library reports (to my horror) that I've got 35 3e and 3.5e in my collection, plus a couple of years of Dungeon and the odd Dragon, as well as Arcana Unearthed/Evolved and Iron Heroes. I'm optimistic about 4e.
I think there are various possible and contradictory relationships between library size and opinion on 4e:
- I've got a bunch of 3.5 books and I feel their worth will be diminished when 4e comes out.
- I like seeing new rules. I buy all the new 3.5 supplements, and I'll buy 4e when it comes out.
I'm somewhat guilty of belonging to this latter camp. I've seen lots of design directions in late 3.5 that I like (and some that I don't). I'd like to see the good ideas they've had become core and get more support.
I'm running an Age of Worms campaign set in Eberron. One of the first changes I made going in was to replace the Sorcerer class with the Warlock. I'm using more flexible casting rules for Wizards loosely inspired by the Magister from Arcana Unearthed - prepare spells each day, and cast those spells freely within each spell level (prepare Magic Missile, Mount, and Detect Undead, but you can then cast Magic Missile three times if you so choose). With that change in place, the Sorcerer becomes pretty redundant, but the Warlock fills the "cast from a limited set of power, but much more frequently" niche better anyway.
I'm a fan of Bo9S, but only in the abstract, as I haven't been able to introduce it in play yet. The Warblade is a great replacement for (one type of) fighter, but it's inarguably more powerful. I could replace the Fighter with the Warblade ala the Sorcerer / Warlock swaperoo, but then I have to a) start worrying about balance between the Warblade and the other PC classes, as well as reconsider every NPC fighter in the campaign, and gee, wouldn't it be easier if all these new ideas were core from the get go?
Don't get me started about Incarnum.
So: I've got a lot of supplements I'd like to see get more use. I think a lot of the ideas I like will see more use as core rules rather than as bastard supplements. And between that and the non-D&D D20 stuff I've read, I know there's room for improvement in D&D mechanics. And while 4e is still in the hypothetical and speculation for the non-NDAed among us, it gets to keep its status as Platonic Ideal D&D for now.