at the moment the emulators support up to 166 so 180 wouldnt really help that much, but its always good to have more options!
I personally run my GP at 166 nearly all the time and it runs genesis great and snes really well too, bare in mind though that full speed+sound is still not perfect on either emu
128 is the max but thats not really a problem since I have around 10snes games, about 20nes ones, about 10pcengine games and monkey island 1+2 and doom 1+2 and some GB games all on one card
there was a hacked version of opensnes that ran up to 200 I think but I think that most programmers plans are to keep the emus as compatible with peoples Gp32s as possible meaning 166 or below...
hmmmmmm, not pointless as such, you *would* get by with a 166 but if you can afford one you might aswell splash out on a 180, like I said sooner or later there might be software that supports higher clockspeeds