The expected engine life of all these RB engines are rated at at least 250,000kms. Read that somewhere, i'll try to put the article up.
The NEO RB25s are improved versions from the older RB25. The 34 shouldn't have a problem up to 300,000kms i reckon. Just look at those RB20s and RB26s in the R32 GTRs, most of them are still running really well even after 160ks.
My 2 Cs