Blew a seam on 1 Skykomish tube cover a month ago, bladder bulged out like a pimple but held. Dave Scadden has offered an upgrade to the Avenger 12' x 18" "V-Tubes" for a good (I think) price. I want the bigger tubes as I have 2 Sky's and have been doubling up the frames to fish stillwater with the wife or Grandsons, but would like to go 18-20" x 12-13'-6" tubes for class II-III waters. I'd like some input from those of you who've used both types of tubes; the Avenger type and the traditional twin tubes. How well does the Avenger do with the 2-man frame vs say a set of 20" x 14' maxxor or other tubes. The Avenger tubes are bladderless, twin chambered on each side if I've got it right.