by default, text comparisons are case-sensitive - the opposite of mysql. you'll need to enable some 'citext' extension (or come up with some other workaround).

There's other diffs, but that's one of the ones that jumps out.

Other downsides in what respect? Performance? Compatibility? Portability? Until a few years ago, mysql on windows was better supported, but I think pg on windows has closed that gap a lot (haven't used it on windows anything beyond a basic install, so can't comment too much).