For me, playing PS1 games on a PS2 makes the PS2 worth owning for "console retro-gaming" (let's call it that way). Buying a GC just to play those few (admit it, its catalog is far from covering every genre) titles alone in my 'computer room" is not something I would be inclined to do (at least, not until the wii or its successor offers similar backward compatibility, if you get my point).
After some more unsuccessful testing, I am under the impression Dophin devs won't pull out another big update for quite some time. What I mean by that : they don't seem to focus on such or such game in particular, which would justify having Dolphin users grab every little update to see if their requested game works better.
In other words, I am not really frustrated about the numerous poorly emulated GC games, although some seem truly great. I prefer PCSX2 approach : A blunt error msg for games with predictably 1-10 fps.
For one, with just a little more work, Super Mario Sunshine could have been so much better on the real thing. Nintendo if you read that, do what you want but don't blow your flagship product again !
About the controllers, I found out about a N64 / PC adapter :
May be the same stuff exists for GC ones ?
Someone has any luck with Beyond Good or Evil (the cutscenes play slooooow here) btw ?