I'd forgot I started this thread, I've experienced the 300rpm chugging thing too it's nearly like a run on, you know you have stalled, but you have to wait a couple of seconds for the engine to actually stop before you can restart it, as pumping the gas or anything else won't get it back to normal rpm like an old school engine.
Having said that I believe it was mostly the engine bedding in, having never owned a brand new engine before I have now seen the motor has steadily got better since about 5000km with a few well loaded long runs helping a lot. It now can chirp the 33" Muddies in 3rd just fine and 2nd gear is more a bark now than chirp.
The bottom end torque seems to have improved a lot, maybe a towing cam and supercharger might be the go later
Yes it now backs up the driveway ok, maybe some getting used to it was involved too but I think it was more the enginee bedding in, as my brother reversed it ok up the driveway a few weeks ago and he'd never driven it before.