There's a script that creates perfect circles from edge selections: vimeo.com/65246315 Maybe you can use that to fix distorted edge loops when you need to.
Usally I dont like curves, because in Blender they are a bit ... meh. But this sounds actually pretty good and easy. Well, it isnt the best solution for everything, because I dont just use this method for tubes, but thanks for this great time @Bartalon @huffer this kind of stuff needs a custom script? nice to know. thank…