I have the Caribbean (pocket body) and it's very impressive. The combination of output, runtime, and tiny size is amazing.
Beam is a nice combination of flood/spot; a little more narrow than my HDS U60, but wide enough for closer work. Mine has a few minor beam artifacts, doesn't hurt utility, just an aesthetic thing. Don't know how typical that is.
Light output appears about equal to my U60 between level 2 (42 lumens) and level 3 (30 lumens), so I'd estimate about 35 lumens.
Re not needing it, I went through the same reasoning process: already had the HDS so why another small light, esp without variable output.
Well it's so small I now pocket carry it rather than the HDS. No fooling around with clips, holsters, etc -- just drop it in my pocket -- it's about the size of a Chapstick.
You could argue pocket carry is what an Arc III or Matterhorn is for. However the Caribbean is nearly as small and puts out vastly more light.
I like the pocket body over the keychain body -- it's smaller and I don't like lots of stuff on my keychain.
Unlike the fancy McLux or HDS, when you receive the Caribbean/Glacier Bay, it looks small and plain. You think "It just turns on/off? I paid $100 for THIS?". Then after using it you appreciate the engineering under the plain surface: excellent regulation, type III anodized, good runtime & output packed into the tiniest package.
Re Glacier Bay vs Caribbean, I figured nearly 2 hr runtime on the Caribbean was enough so decided higher output over longer runtime.
SL PP Lux 4AA, Peak Caribbean, Chapstick