I cannot comment on the PEAK products as I do not have any of their products.
I am looking forward to seeing what offerings they have in the future, however, and how their products hold up. Their "design your own light" concept seems very interesting.
I can say that I have been very happy with my ARC products.
I own
1 ARC LS (old version) factory second
6 ARC AAA Turquoise
1 2002 CPF ARC AAA le (later sold)
1 2003 CPF ARC AAA le
1 3.1 ARC AAA (gave as a retirement gift to a Pastor)
1 ARC AA
(I am waiting for 3 ARC RGB lights in the mail, as we speak!)
1 of these, an ARC AAA Turquoise, resids (facing forward, like a headlight, not down) on my dog's collar, and it gets wet regularly, like several times a week, and I have had no problems at all with the light.
I am VERY VERY happy with the performance of the ARC AAA Turquoise on my Dog's collar. It works as well as I dreamed or invisioned it would. At night, I turn it on whenever she runs free, so that I can see her, so that others can see her, so that she can be seen by cars, and I think she actually likes being able to light up whereever she goes!
If you have read about the problems that ARC has had with their lights, jusr for the record, I have had only one that gave me any problems, my 2003 CPF ARC AAA, it sometimes does not turn on, but completely unscrewing the head, taking the battery out, and putting the battery back in, and rescrewing the head, fixes the problem.
I am going to send it in for replacement at sometime in the future.
Hope this helps.