All comes down to fun; you said you aren't having fun with it - don't bother with it; BUT if you do become curious again...flip it and see if you've changed your feeling towards it.

Not sure if I'd like riding with that gear ratio - I ride quite a few hills so I'm sitting at 48/18; not sure how much of a difference it would make compared to 50/17. I wouldn't be overly concered about the knees unless you really feel the need to skid.