one of those things that are subjective. theoretically, one should not need a colder stat than stock. however, our cars are older and not so efficient. so if you are running hotter than you would like (radiator and other cooling system stuff not workin as well as it once did), a 180 is sort of a band aid or crutch to help it out.
the best thing to do is replace/renew parts to get the system back up to par, but most of us cant afford to do that...........
IIRC the puter hits closed loop at 178*, so that is a magic number to look for.
i know of some whom run 160's and have decent milage. i think their system is not up to par, and they still run 180-ish or more.
one can also use a 170* stat from an infiniti if desired (i know you have a 180 already).
as for bad sides - i cant think of any. i live where it is very very hot, so i dont care much. i do whatever i can to keep the motor cool. if you are running too cool, that is bad. oil and the motor itself needs to be decently hot (for efficiency and performance), but in the real world, i dont want to be on the outer limits of that realm. plus you guys run hot and have detonation issues anyhow.... as long as you are makin it into closed loop, you should be running fine with no ill effects.
that is about all that comes to mind. good luck.