Anyway, I know a few people are interested in these lights so thought I'd do a quick comparison with my trusty 70w metal halide. Both lights were suspended 50cm above the water, camera was on a tripod and in manual mode, with white balance set to 4150K which best matched my perception of the room without either tank light on. I think the results give a fairly good idea of the rendition of the two units, but make sure you're viewing them in a colour managed browser (ie, not Chrome or IE) if you want an accurate view.
Impressions so far after 2 days with it.... overall I like it. It's very small and means I'll be able to retire my somewhat ugly lighting frame and get a more minimalist fitting of some sort. The colour rendition is pretty good (I tried one of those cheap ebay floodlight LEDs once and it was ghastly, this is much better and nicely contrasty without giving harsh shadows).
The one major issue I have with it is the noise of the little 40mm fan - it's louder than my quite powerful PC and you can hear it over pretty much anything else in the room. Definitely enough to be annoying in a bedroom. I've opened the can up and it looks like its a standard PC northbridge style fan, so I've ordered a supposedly quiet replacement fan and I'm hoping it'll be pretty straightforward to swap out.
So... 70w halide with (I think) a 6000k bulb in -
And the Kessil a150 (rated as 6700K) -
So, not actually much different!
Afraid I don't have a par meter to check that, but visually it looks similarly bright to my 70w halide. Photoshop reckons the cropped underwater section of the image is about 20% brighter with the Kessil, which seems believable, although this is obviously a pretty spurious metric.
Edited by BigTom, 29 March 2013 - 08:47 PM.