I mentioned this in another email thread yesterday about a similar topic, but I'd highly suggest if you do go the UUID route, do not use the standard UUID generation functions, they all suck for database use (v1 also sucks).
I don't mind having a time component correlated with my UUID's because it's simply not a threat model that matters for my use case, so I use the time based variant. It helped me immensely with FPW and
write amplification when I switched from V4 UUIDs. It is still not as fast as an int, but it is much much better than random UUIDs.