Hello,
I have been runnig the saito 180 in my dp ultimate for about a year now. Auw is 11lb 4oz. I think this is a really good combo. I am using 18x6 mezjlik with cf ultimate spinner. I also run 30% heli but I've never reached 10k. I am at 4300ft so this may be attainable at seal level? At first I was seeing about 8500. I opened up the cowl a bit and did some duct work to get all the air flowing over the cylinder head and gained 1050 rpm! So right know it max's at 9550 but I detuned it to 9300 for consistancy. Since the mod the ultimate now has unlimited verticle. And good pull out from a solid hover.

b0gh0s,
That seems a bit weird that it doesn't flatten out in the spins. Do you have enough throw? if so you may be a bit nose heavy. My ultimate gets completely flat with about 75-80% elevator at 100% it goes nose up and starts to wobble a bit. This is both up right side up and inverted.
At first i didn't like it for 3d. The key is to get the cg back. I ended up about 1/4 up from rear cabin. With an aft cg this is a totaly different plane. harriers up right very little wing rock, none while inverted and it is easier to manage in rollin harrier.