I have found the temperature effects bladders quite a lot, if it is cold outside.  40 degrees and below.  I have been told there is a variety that is fine in the cold though.  I have used thicker walled quite a bit, and it does fine, and in fact I think it is primarily what I have used in the past.  They just require more effort to inflate, and take a little more time to train, but they last longer.  More pressure can actually make it more tricky to set a needle as well.   Like I said in the Head shim thread,   I used all of the exact same items, NVA, Prop, Bladder,  plane.  I just swapped the engine, and it worked fine, so the bladder was/is not the issue in my case.  I use the same bladders for my 1/2 A and my Speed limit models now, and I think it is of the typical 3/32" wall thickness.

Phil gets it from somewhere.  McMaster Carr is a good source.   Also, you can bleed off any air before running engine if needed.  Naturally the lack of air in the fuel system is one of the benefits of the bladder tanks.  The lack of air may actually be more important than the pressure itself as has been discovered through the widespread use of the baby bottle bag tanks by the brand name of Tettra, or Jettstream that Dub Jett sells