Striker,
I was using an OS .91 FS and tried quite a few props with it, the 15 x6 was by far the best balance for thrust to speed. 14" props seem to be fighting for a grip on the air, wasting a lot of energy and not holding the plane up except at full power, at least in my part of the country. The .91's are pretty closely matched when it comes to RPM's and power output so name brand probably won't make a difference to the performance in the plane, I think the OS is a bit heavier though. The APC 16 x 4W is the best prop for hovering but a .91 really struggles to spin it and the throttle response was pretty sluggish which is not what I want when hanging a couple of feet off the deck. I also found that the plane doesn't want to T/R easily with anything else than the 16 x 4W, the 15 x 6 will do it but very slowly, 14x 6 and 15 x 4W wouldn't do it at all on my plane.

With mine the balance is right at 6" back and I really like it there. Like you were saying you have to point the plane at the ground and resist getting on the elevator till it's just above the ground when landing. At 6" it's not bad at all but at 6.25 mine got difficult to land in the wind and all it took to get it there was 1/2 oz. stuck on the tail right in front of the tailwheel. With the tank on the CG you really SEE the difference a minor change in CG can make and I mean RIGHT NOW! I think having the tank on the CG really helped with inverted stuff as well since I don't have the weight up front trying to drop the nose through the first minutes of the flight.