I ran the Xray XT8 for a long time until I decided to drop that class. I never had a single diff issue with it or any of my buggies. It uses the same exact diff as the 808 and everyone knows those are rock solid.
I wouldn't consider it outdated either. Sure it's been unchanged since 09, but there's not much there to update. They have new shocks for the XB9, maybe try them on the XT8, but that's about it. It handles excellent and is one of the most durable trucks on the market. I got 2 1/2 seasons out of mine and it was still in great shape when I sold it.