I have this set up.
Great Planes, .40 size floats and .61 2stroke engine. I originally had a .46 but definitely didn't have enough power for these floats. It flies decent with this set up, but different then without floats. You will need positive incidence in the wing to the floats. If you don't, you will have a very fast boat that stays stuck to the water, until top speed is obtained, and full up elevator, then it goes vertical. But, once I got the wing to float incidence correct, it lifts off the water gradually, without full power, very nicely. Also, the step is behind the CG.

I like it because I really like the Sig SE. This is my third one.