The X+ is HTC's red-headed stepchild (um . . . no offense to red-headed stepchildren). A mid-year incremental upgrade to the One X, the X+ was sold in extremely low numbers, with little support from HTC or the development community. The X+ was condemned to obscurity form the start, to say the least. I'd stay far away, as the slight increase in CPU power is not worth the downsides.
That said, unless you are really strapped for cash, do you really want to spend your hard earned money on phones that are a year to a year and a half old? I'd consider a more current device, especially if you are worrying about gaming performance.
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Phone: HTC One X (AT&T version) Rooted, Bootloader Unlocked, S-Off
Tablet: Samsung Galaxy Note 8 (WiFi only) Rooted