Yes, I've tried Fluxbox and IceWM, as well as XFce, although I realise that's a desktop environment, rather than a window manager. Yes, they're certainly faster in general, but don't quite have the "snap" of a smooth running GUI. I think sometimes it's the app as much as the desktop/wm. Dello loads in a flash, for example, while even Opera or Firefox take a little while.
I'll happily go with a wm if necessary, but I'm still left with the problem of package management. I have some spare disk space, so Knoppix will go on tonight if all goes well.