Most of us understand the frustration that comes with these machines.
Backfiring is a sign of lean jetting, what mains do you have in right now?? Are you running pods? You may even want to try your needle on the 4th clip, because you said your problem seems to be at 1/2 -3/4 throttle.
I have the exact same bike as you, mine came stock with 200's also and ran like a raped ape. If you are running the stock airbox w/ K&N you would prolly be at 280-290 mains, i really think you should try 330's if you have pod's.
I think that the new needles and bigger mains will fix your problem.