I own the 3 LED Ultra and it is really impressive for a single AAA light! It's a lot brighter then my Arc AAA. It is also my only EDC and I use it all the time.
I have not heard about Peak dissuading people from buying the Ultra power, and can't find anything about that on their website. I'm sure the increased output does shorten the overall life of the LEDs however.
By Peaks ratings (posted on their website) the 3 LED Hi Power is twice as bright as the 1 LED Ultra and still runs for 3 hours to 50%. The 3 LED Ultra is about half again as bright as the 3 LED Hi Power and runs for 2 hours to 50%.
In my book that makes either of the 3 LED versions the best values. If you want the brightest go 3 LED Ultra, if you are concerned about the lifespan of the LEDs, go 3 LED Hi Power.
Honestly though, LED technology is advancing so rapidly, and I like buying flashlights enough that I don't worry too much about LED lifespan. I doubt I'll have this flashlight on for more then a hundred hours total runtime before I end up buying the next great little flashlight in another year or two.
-Brian