I picked up a Black Wiimote and Black Classic Controller Pro yesterday and hooked it all up, works like a charm. 12 buttons to use at my disposal and it is super fast, no latency or lag. It looks and feels like a playstation controller, so PSX4droid is beautiful on it, not to mention all my old school emulators work brilliantly on it as well.
Theres only 2 downsides to this setup. The first is that you have to lug around the Wiimote AND the classic controller at all times, if you plan on gaming on the go. The other downside is that using a seperate handling device means your phone has to sit somewhere. This can either be easy to deal with (kickstand on a table or desk) or it can be a nightmare (leaving it on your lap, 5+ minutes and you get neck strain.)
Other than that this works awesome and I fully support the dev who wrote the Wii Controller IME app as well as using this setup. Now if only I could output my phones entire UI via HDMI to my 62" HDTV...