I have flown two of the SSE and loved both. I believe some of the modifications mentioned here will make the airplane too heavy. It is borderline heavy as is for a 46 engine that is not to say it won't fly well with a 61,91, 80,75. I personally liked the Tower 75 best on mine. With the larger engine you will get more air blown to rudder, elevator to give better knife edge etc. and naturally it flies faster and really comes alive. I added extra rudder/ elevator to my first sse but I prefered the second one with stock control surfaces and larger engines. You must be able to change an airplane with larger engines to compensate or lead will kill the airframe. (longer fuse in rear, shorten firewall, servos in tail)
I like the counter balanced controls but haven't tried them but if I build another I will give them a try.

Please go backup and look at the picture of Saito 91 above, its carb positioned at same level as the top of fuse, too high for consistent fuel flow. Mount motor on side and this puts carb in line with center of fuel tank and get consistent fuel flow.