So, I've just gotten my hands on a Boost LED lamp (BLL) myself, not too long ago -the one I have has 40* optics, with a 4b/1w color combination. There are other LED color combinations you can choose from on Boost LED's website, IIRC. These lamps burn 10w total, each.
In any case, I am currently using a single BLL in conjunction with three Evil Par38's lamps from Clive over at Nano Customs over my reef tank. I have the 12k (3w/2b) par38's, two with 40* optics, and one with 60* optics. There is also a 3b/2w 20k option. I believe these lamps run (5) 3w Cree LED's per lamp; each lamp consuming about 21w.
My initial thought on the Evil par38 lamps from Nano Customs was that, wow these are fairly large, and heavy. They do get warm after being on for a while, but that is what those wonderful heat sinks are for. The heat sinks get warm to the touch. I have not been let down by these lamps, as they're really very powerful, IME. If you're tank is large enough, you will need a handful of these lamps to get equal, for satisfactory coverage IMO -and at $88 per lamp, this can quickly add up in cost for most people. If you have a nano tank though, say in the 20g or less range, I think these lamps are ideal. Any larger, be prepared to drop some dough. But wow, with the 40* optics, these are fabulous little spotlights.
All in all, the Evil lamps are good to boot. Strong, built fairly well, and great PAR -and I'll be honest, they look good.
The BLL's are $70 ea. They use 3w Edixeon LED's, though I'd suspect that they're not driven to their maximum. If you're looking for an economical 1-2 lamp solution for a small tank, under 10g, I think this lamp works great. Being that the BLL is a par30 lamp (compare to Evil's par38) the form factor of the lamp is much smaller, and much lighter. Also, the BLLs are very well built, and very sturdy. More sturdy then the Evil lamps IMO; though Evil's lamp are no slouch either. But let me just say that if I dropped one of Evil's lamps, I don't have much confidence in the lamp holding up. If I drop a BLL, I would be more worried about whether or not the floor was damaged instead of the lamp. The heat sinks on the BLL also look, and feel substantially more sturdy for the thin rayed heat sink on Evil's lamp (you can literally cut yourself on them if you're not careful).
The BLL seems to run a little bit cooler than Evil's lamps, maybe the difference in power consumption may be the cause of that (I'd imagine).
The BLL are pretty powerful for what they are. But when I placed the 40* BLL next to my Evil 12k 40* lamp the Evil lamp clearly beats out the competition. I am using the BLL mainly to add a touch (literally, a touch) of blue to my tank, and it does just that. I don't have a par meter, and haven't looked at the par plots for the BLLs, so I can't speak on that.
Though, if I had to choose one lamp to use again -I can safely say that I would definitely go with the Evil's par38 lamps. At only $20 more per lamp, you get quite a bit more power IME. But again -the BLL are nice as well.
And as a side note, I'm going to agree with Gresh -the customer service with Clive is one of the best.
Hope this helps.