Is a rubber keyboard suitable for heavy use?

I was once optimistic about them for the reasons you listed, but found them to be absolutely horrible in use. The keys quite literally wobble back and forth on their downward stroke, so unless you enjoy battling little mounds of jelly, avoid.

You should go to a hardware outlet and give it a shot. I really can't recommend the things for anybody. I think typing would be marginally faster than an on-screen keyboard.

There are probably no reviews because the things cost a few bucks and nobody loves them enough to express it on a review site. Simply another buck or two thrown away.