I'm looking at getting some more expensive rods, but the ones I like have cork handles. I've always gotten eva foam because I think itll last longer. Has anyone used u40 cork sealer, and if so, does it keep the cork from splitting, pitting, and shrinking?

The short answer is yes.  The detailed answer is just do a quick search on U40 and you will get more info than you will probably want to read.

never had a cork rod handle wear out so never bothered sealing it.  It does make it look nicer for longer though.

I sealed mine seems to works pretty good, didn't notice any difference in the feel. Also a thin coat is all you need.

Yes, one coat only, will stay cleaner and will clean up easier.