I'd guarantee you'd have to dump as much into the Explorer as the Xterra. I'm sorry but as much as these guys say get the Explorer, they have a bigger problem if your not careful which will cost more money than the timing belt change on an Xterra ever will. If you do the TB change yourself on the X which is about 2 hours for a novice it will cost you between 275-300, dealer will charge 500-700 for it.
Brakes are dependant on driver, 70k out of brakes is quite a bit as most people average between 20-40k. Lower cost as well as only the fronts are disc brakes and the rears are drum brakes.
The Guide chains, and trannies on the Explorer(if not cared for, which most aren't) are the weak points in the one engine, and the trans configuration.
Your getting opinion from both sides, I really recommend you read up on both of them, find out what else you need to know and make your own choice. Basing it off what everyone else says will land you with a ride you will not enjoy. Take them both for a test drive etc, see which one is more your style. I think the X is a better looking ride but to each their own
Inspect vehicles for rust, records, check under carriage and give it the suspension test. Take em for a test drive. Guys are easily getting more than 200k-300k out of Xterra's just like the Ford guys, but again its dependant on what your looking at. Most cars are neglected and its those few that aren't your trying to find. Check trans fluid etc.