I'm not a interviewer, but I would view packing in instructing becuase you thought nothing else could be gained from it would hint a little bit of arrogance.
i am sure you agree Delta T that you never stop learning in flying. And that is one reason you should keep going. The more experiences good and bad you have, the more you can chat about at the interview! I agree totally with S&L.
I got my command very quickly due to my amount of hours built whilst instructing. And I am hoping it will hold me in good stead for a Training position to.
If you really don't enjoy it now though. Then I do suggest you give up as it will reflect in the quality of instruction given. I am not suggesting you are, but you need to be honest to your students if thats the case.