I got two today, one gave me a bit of trouble removing the head to install a CR123 body. They're not loctited or glued, just real tight. Sound's weird but I wet the head and wrap it with a piece of foam rubber packing material, gives you a better grip. Threads are standard - righty tighty, lefty loosy. Just keep at it. One other thing, the O-ring didn't make it through the disassembly, it ripped probably due to no lube - good thing they come with extras!
Rob
PS- Make sure you lube the little thin O-rings on the 123 body - they look fragile, I use Radio Shack Multi-Purpose Lube Gel, others may say to use Nyogel, but it's not available easily.
PPS- You will love the L2P head with 123 body! Lightweight, small, bright!