Actually, I think the HD was a better light than the 16HD. IMO, the wifi connection of the HD is better than the Bluetooth connection of the 16HD, the HD lenses are much thicker than the 16HD lenses, and the spectrum of the lights isn't different enough to go, "I have to have the 16HD!"
With the HD, you also get the side benefit of being able to upgrade the LED pucks to
@luxdium to get arguably the best, widest blue spectrum of any reef light on the market. I actually had a few 16HDs but, when I found LuxEngine, I sold them and went on the hunt for more regular HDs. At this point I have upgraded 7 Prime HDs and 4 Hydra 26HDs, and they're all I run.
When I find used ones like that, I take them apart and clean them really well inside and out, and I replace the fan ($12) and lens ($7) while I'm in there.