I can deffinatly back roger up on the whole 44 cm fin thing. I don't usually use the 42 cm fin that came with my hypersonic 111 at all!. I use my 34 cm fin all the time with a 7.6 fully powered to a 5.8 juiced in lots of big chop. I would only use the 42 fin when I am very underpowered with my 7.6 and am trying to get planing... (around 12-13 knots)
As for chop, so far I have taken it out in roughly knee high (2-4 feet max) chop. The board is ok, its almost too fast in that stuff though. I hate going into chop, cause you just bounce around everywhere, and its also unnerving sailing downwind with such a short nose... I swear I have blown through a couple of smaller chop and almost eatin it on some speed runs.
As for sailing the hypersonic in general... WOW, I wouldn't recommend it either for a beginner board. I can't imagine sailing it or any other fast board out of the straps and harness. The only way you are going to feel comfertable at all especially is when you are in the straps. But try learning to get into outboard straps on a different board. The hypers strap settings are very outboard. Sometimes when I am sailing, I get a face full of spray from my heel in the water :-)
I attached a picture that I think shows the proper trim for the hyper. I am sailing reasonably powered with most if not all of my weight in the harness, pushing across the board instead of down and lifting my front foot driving the board upwind on the lift from the fin. I could let go of either arm, which I did my front arm right before this was taken. The only thing I think that is wrong is I should have dropped my front shoulder a bit more for the upwind angle I am trying to achieve.
As for tuning, I only ever have the mast foot half way up the mast track. Its mostly at the bottomish depending on how loose I want it to feel.
Hope this helps,