I have been playing with altering my original diy grizz bridge. I figured since it wasn't cosmetically elegant enough to sell that I would sew up tthe bottom of the hammock to see what ratio would work well for me. My spreader bars were 36" and 28" per grizz's design and I have altered my ratio a few inches at a time down to the 1.15 that you are using. I weight in at ~175lbs and the easton poles have handled that ratio and my weight just fine.
The problem I am having is by altering the material arc to that ratio it is getting too shallow and in the middle too narrow. My bug screen is a little close for comfort and in the middle the material doesn't come up over the sides of my midsection so the bug screen is up against me in places. I had planned on going to going to 39" and 30" spreader bars and decreasing my depth of the side arc from 7.5" to 6" like yours. Hopefully that will be just enough to fit better in the middle and work better with the bug screen.
The 1.15 is definately more comfortable. I have slept on my stomach in my Grizz style bridges in the past for an hour or so at a time, but couldn't take it for longer periods. I think I can sleep on my stomach with the new ratio. Tippiness has increased, but surprizingly less than I thought it would. What has changed with the tippiness is that I don't sit as beep in the bridge so there is less material on the sides to grab or lean against.
I have my carbon fiber poles on order and will start bridge number 3 soon. Hopefully this is my last bridge for me anyway.