For me a shakespeare expedition, the only tube I've used but the second I've owned. For me I think you MUST put safety first and you are right to ask the questions you have. I've used my shakey about 20 times now and its pretty much for me sound as when it arrived, so build quality seems fine. The 5 bladders are all lifejacket quality and the tube for me is ace, the only addition for me is the sparton seat cushion which for me sorts out the only issue the shakey has, though I've not used mine in high winds so can't comment on its performance in those conditions.
The other tube I owned was a cheapo off ebay that had a single lower bladder of really cr@p quality like a kids lilo... Go out in 50 foot of 10degs water for a few hours? It doesnt really take much thought.
Then again, whatever floats your boat!