I think it comes down to what you want. Basically a bolt action rifle and in .35 Rem, not a handgun cartridge. While a very accurate platform, never very popular. The introduction of the new magnum handgun calibers in revolver platforms and the popularity and versatility of the TC Contenders has hurt the already small XP100 following. With many states now allowing straight-walled handgun caliber handguns and rifles where once only shotguns could be used, I personally could see the viability of the platform in a true handgun caliber. Not so much for a rifle caliber.
But that's me. Again, a very accurate platform and has been said, very few folks at the range have ever seen one in person. If you like the caliber and the platform intrigues you, you already have an answer. Go with what you want/feel, you don't need us to justify it to you.