Two-handing can be done in a relaxed mode due to the support of the second hand. If your back is in good condition, it shouldn't pose a problem. The stresses on the hand, wrist, and shoulder seem lower compared to one-handing. I've been having trouble with my left hip though. (That's part of a pre-existing condition.)
I didn't notice the two-handers having any problems that anyone else didn't experience. They did well, qualifying for two events each. I'm curious about the number of people who qualified on multiple patterns.
For some reason I don't think of two-handing as a power technique. Maybe because I lack power for now? I just see it as a way to deliver the ball.
I understand the feeling of two-handing being promoted or pushed to an unreasonable or annoying degree. As a person who enjoys alternative techniques, it's common to have one-handed hook bowling pushed and promoted at me. heh And I have been overzealous at times promoting my preferred flavour of the month. What I find time and again, the more I think I've learned, the less I really know.
My wife, for example, has some non-textbook elements to her game. I was thinking yesterday that we should work on those things, especially her swing timing. Then I came across a video of Diandra Asbaty and found that she does things in a similar way. Who am I to argue with something that works?http://www.pba.com/Bowlers/Bowler/37075