Performance-wise I don't notice a difference between a 2-piece and a fused 1-piece. If I break the blade on a fused 1-piece I'll generally cut at the fuse point and chisel out the old tenon to turn it into a tapered shaft, if I replace it with a high end blade the performance doesn't drop at all, in fact sometimes it improves if I put a better blade in there
Harder to say with 2-piece vs. some "true 1-piece" sticks. People have different definitions of what a true 1-piece is, but IMO if there's no tenon/thickening of the shaft walls at any point, that's close enough to a true 1-piece (others say its only a true 1-piece if the carbon strands run the whole length of the stick, but I'm pretty sure Busch is the only company to make a stick like that). Sticks like the Warrior Widow and Easton S19 are pretty unique sticks, you won't find a 2-piece equivalent, if you want something like that then a 1-piece is the only way to go (there's a 2-piece S19, but it's totally different than the 1-piece, it's basically using the same idea as the old z-bubbles). But if you're trying to decide between, say, a 1-piece or a 2-piece Warrior Dolomite, then there's essentially no performance difference IMO.
Personally I love tapered 2-piece setups, not so sh1tty/expensive when you break the blade or shaft, and it's nice to be able to switch out curves. The only downside for me is that they're becoming pretty rare, to get a really good selection of blades and shafts you need to find a great LHS (in Vancouver, for example, The Hockey Shop/Source for Sports in Surrey is the only shop I've found that has a really wide selection).
