I put a 10 speed Campy wheel on a bike with a 9 speed Shimano chain, and old Campy SR friction shifters and derailleurs, and I expected it to not work very well. I wasn't sure that the chain would fit the sprockets without rubbing or even worse, getting stuck and seizing.

What I found instead was complete silence and smooth shifting. I expected it to be fussy at the least, but it wasn't at all. The only thing I couldn't do was get it onto the largest sprocket as I ran out of swing on the shifter. Front shifting worked fine also.

I guess you never know what will work until you try.