APC 3.1.14 on PHP 5.4.11 - had segfaults with apc.stat=0 and apc.lazy_* segfaulted too, so had to disable those; but otherwise working well and serving 450+ requests per second with very little fragmentation (tends to happen in the latter part of the 24 refresh cycle).
I had considered Xcache but as APC is still being actively developed I just decided to stick with what I know.
And what about eAccelerator? If you have a cPanel server, it's an easy install (Xcache comes unconfigured). The latest branch is supposedly compatible with PHP 5.4.x, and it's pretty reliable. I think the performance differences among the various caching scripts are relatively minor in the scheme of things.
Had problems with APC initially when we first installed it, but we'd upgraded to a later version and it has worked without incident for 4+ years now. No desire to change or try another since this just works.
The benefit? It cut our server load numbers in half! Any opcode cache is worth installing IMHO. Use whichever one works right for your server.