OK--I get to ask my own question. My Hobie i 9 inflatable arrived today. It was yellow instead of sage, and probably a better color, because it is more visiable on the water. As a long time, long distance sailor and now power boat operator, often dark colored or neutral colored kayaks are difficult to see in heavy conditions or limited visability--thus I bought an orange Revolution.
The boat came with the standard fins, and the technician was not aware of the mast change, so the ST TURBO's ai bought would not fit, but the ones form my Revolution did fit and worked fine--even though they have the different latch mechanism.
With the ST Turbo and a cadence of 60 I was going about 2,8 knots--for me in the Revolution, I would go going about 3.8 knots at the same cadence. At a very leasurely 45 pedals a minute I was going 2.2 knots. Max for me at 90 pedals a minute I was only up to about 3.4 knots. The Revolution would be about 4.5 knots under the same cadence.
Surprisingly there was little difference in speed with the standard fins and the ST Turbo. The boat felt more solid and felt more powerful; If I was towing or bucking a head wind, I am sure that the Turbo's would have given a slightly higher speed. However, the limiting factor is the hull form and the length of the water line. With the same amount of power, this shorter and fatter boat, will just go slower.
General impression--the boat was very stable, and I am sure I could get back aboard with no problems. With my weight (about 190 lbs) the boat didn't slip water, but if any got in, it seemed to pool around the seat (even though the boat was inflated at 5 PSI). The boat tracked well, it turned much better than the Revolution. In the Bayou behind my home, the I have to get the paddle out to turn the boat in 40 feet--the i 9 turned in 20 feet or so. Even with my back problems the seat was comfortable for me. I had to tighten up the side straps, so that the seat was almost leaning foreward, then I could lean back against the padding and get support.
The boat will work well for us--it is used as a second kayak. The Revolution is used on a daily basis, mostly by myself. When we take the larger boat (A C Dory 25 in Dana Point) or a Tom Cat 255 (Pensacola, Fl), we will carry the Revolution on the roof, and initially the i 9 deflated in the cockpit. After inflation, it will go on the other side of the cabin top. It will be easier to launch than the Revolution. It will be used for "shore duty" for our small dog (who loves riding in the kayaks), when we don't pump up an inflatable dinghy with a motor. It will also be used for fishing and touring, when my wife joins me (she will get the Revolution). I have fished out of inflatable dinghies for years, and no fear of hooks or gaffs.
I would not buy one as a touring boat, but as a dinghy or back up boat. I have not yet used a sail--I guess I could modify the Revolution's mast and put on shrouds.
I have some photos, but will have to post them on another site, before I can link them here.