I have about 35mm prebend and diamond tension is about 33 on loos. I've fiddled with Ashby's settings and currently use an Ashby main for uni rig. I have proctors but I haven't adjusted them from the stock settings of 50-55mm of rake. So you're right, 25mm is not much. But 65mm seems excessive. In fact, I was actually thinking about decreasing the rake and prebend a bit but tightening the diamonds slightly to compesate for less rake.

I'm no lightweight, but I've found the superwing to be the bendiest alum mast I've used and more flexible than the Stealth F16 carbon mast. When a gust hits, I can lean further in the trap and get the top to spill air. Also, I can bend the heck out of it in the other axis with the downhaul alone. (My only complaint about the Taipan mast set up is that the diamonds cannot be adjusted on the water or even between races.)

If you rake the spreaders more, you'll have to decrease the diamond tension to prevent overdoing the prebend, and then the guts of the sail will only get more full in the gusts.

Can't you get enough on-the-water adjustment with the downhaul alone? It sounds like you want more adjustability--are you going to change the way the diamond wires are rigged? If so, let us know how you do it because that would be a great modification to the standard Taipan rig.

Sounds like the root of your problem, though, is the sail itself. Although I don't think my Ashby F16 main is faster per se than my Goodall standard 4.9 main, it behaves much better; i.e. it twists off to gust nicely, making it alot easier to keep sheet tension even without getting overpowered. Also, Ashby puts these little mini battens at the top of the sail, which give the sail a very streamline profile and never any fluttering. Photo attached of the Ashby main--note that this was his first F16 sail and the fat top is only slightly bigger than a standard 4.9 sail.