The Fenix L1P wipes the walls with the X1. It's a bit shorter, lighter, and has a much better switch (the momentary on the X1 is pretty useless). The L1P has a very bright (for a 1AA) hotspot, much brighter than the X1. The sidespill of the L1P is dimmer than most lights, but the X1 has none at all.
The L1P does have a much shorter battery life than the X1 (1 hour compared to 8 hours), but even at a drained, dim output, it's still brighter. Use NiMH rechargables, and you get a flatter (albeit a bit shorter) discharge curve, but all you have to do is charge it up again.
There's 2 camps of people regarding the Fenix. Some aren't impressed at all, saying there's better, brighter lights (which is true), but others, like me, are impressed because of the form factor. A Nuwai Q3 will outshine an L1P, but it uses expensive CR123A cells, while the L1P uses plain old AAs. At the moment, the L1P is in a class all by itself. There's some other in the works aparently (Peak, Arc?), but the L1P is the only single AA powered 1W Luxeon light out there, at least the only one worth mentioning.
Of course, the Fenix is 2.5x more expensive (about $45).