I rechecked the balancing and found that to be off. So i re balanced the carbs at 2k revs, and adjusted the mixture. Flat spot gone, was great above 4k all the way, but idle was pants and still hanging. Adjusted the mixture more, and can't seem to get rid of the hanging (though again this is temperamental). So i have put the mixture back to roughly standard.
So here i am with a bike that runs great above 4k revs. Pulls cleanly all the way, really taking off at 8-10 as usual. Whack the throttle open, no hesitancy. But below 4k especially when pulling away, it is pants. If you open the throttle fully, she really bogs down, gentle seems better, though that may be my imagination. Its as though the fueling is completely off, though as i say, whack it open, bogs down and very hesitant, get to 4k and its absolutely fine!!
So what do people think is wrong?

