We've had the SLX lights for over a year and absolutely LOVE them!! Not only are they fabulous for daytime diving, but we found them to be perfect at night and to use as focus lights for night time photography as well. One thing we noticed on our live aboard trip this summer was how white these lights are at night particularly when compared with other divers' lights, which ranged from blue to yellow.
Although the Nocturnal Lights aren't cheap, you get FAR more than you pay for IMO. Oh yeah, and the customer service Tim has always provided has always been spot on.