personally I hated the M9, and the 92fs is too similar for my liking but that is neither here nor there.
I am one of the guys that sees no purpose in owning exact duplicates, however similar models with different functions is ok with me. for instance I've owned several springfield XD, XDM, XDS, and XDe, but all in different calibers, and sizes. I've owned 2 1911s, both different sizes and calibers. owned 5 AR15s, all in different sizes and calibers. the list goes on and on but I think you get the gist...
your milage may vary.