Let me just say what I know about the Otter. I had a 13' one, and didn't really like it. The floor came up really high, which forced my knees up high, which conflicted with the oar stroke. It also severely limited gear hauling capacity, since you have less free space between the frame and floor. It also didn't really track that great. Maybe they've fixed this problem though?
Since you're R2ing, that shouldn't matter as much except you won't have much height in the boat for your legs. Hypalon is heavier than some other types of material, but with Aire's bladder system I don't know how they compare.
I don't have any experience with the Aire Boat at all. Many people love them, esp the warranty. The Otter is a thinner grade of hypalon than their expedition series, which will help with weight.
I am a river, babe - I've got plenty of time, I don't know where I'm going, I'm just following the lines..... - "We are water" by Shaye