Clean they respond like a fat single-coil, much nicer than a clean humbucker sound. With really high gain they get too mushy (IMO), unless you're going for a stoner/doom metal kind of sound.
I think they work best for clean tones up to gritty blues-rock tones. I've said loads of times that I don't think they have the tight crunch of a humbucker with distortion (but others, much better players than me, will probably disagree).
I think your MQ neck plus bridge humbucker combo is a good idea, and loads of people on the forum have done that - with all sorts of different bridge HBs, from the Riff Raff right up to the Warpig.