I never geared mine and am not going to either. I found what I think is the best standard prop for a Spd 400, it's the GWS 7x3.5 DD prop. This plane struggled and needed an occasional hand launch at the sod farm I fly at from every other prop I found to be sucessful for spd 400. These 7x3.5's cut down the length of runway needed in the grass in half or better. It also has a noticeably longer flight time and can be throttled back much farther to stay up.
The most important mod that has been found and is now mentioned in the instructions is to angle the front of the motors down if your radio can't mix down elevator with throttle advancement. Not doing this can VERY easily result in a crash. Right after take-off, the plane shoots straight up almost uncontrolably and then stalls. Mine almost fell on it's tail, but the nose fell just at the last second and I spent the next 3 minutes trying to get it on the ground without crashing. My radio doesn't have this type mixing so I had to angle my motors, I used 3 layers of 2 sided foam tape cut into different sizes. They are flush with the front of the motor but look like steps on the back side, this gives a ramp effect. Still needs just a slight amount of trim adjustment, but I have never seen a plane that doesn't change with throttle changes. Along with the tape, the motors are also glued with Foamsafe CA.
These props worked so well that I changed all my spd400 planes over to them.
In regards to eliminating torque effect, there are unfortunately not too many options, but the torque on this plane isn't even noticeable with it's overpowering tailfin and 5 lb flight weight.