I use to use bladder tanks in pylon racers and that has been considered the "norm" for quite a few years now. In this case, they use a flexible bladder inside a rigid plastic tank housing (looks just like a normal tank) that provides support and protection for the internal bladder. It takes a bit of getting use to filling them but it soon becomes just another way to reliably supply bubble free fuel to an engine.

With all that said, I still prefer a normal tank for all other applications as they work reliably and they are simple to set up and maintain. All the rage now is the clear, water bottle style tanks but I have not been bitten by that bug yet as my old conventional model tanks still provide good, reliable service at less cost.

Full scale aerobatic planes still use a clunk setup in their tanks as it is a proven setup that has stood the test of time.

I'm certainly not against bladder tanks. I just feel they have their place in limited applications and are certainly not for everyone. For the average guy, I could see them causing more problems than they solve.