I bought the Big Bee ARF too, after many flights with my small lazy bee's I figured the big bee arf would be just as much fun. I had 3 of the small ones powered with a Magnum 15 and they were fast and flew great on rudder and elevator.

I have not had my big lazy bee in the air yet, but I have made a few beef-up's.
All of the frames under the wing - I added doublers so I could grab the fuselage without squeezing the sides together and breaking the frames.
Added tri stock to the firewall as best I could using epoxy.
Removed the stock landing gear and beefed up the flooring and added an aluminum landing gear with 3.5" wheels with a 14 wheel base and 6 inches tall.
Beefed up the tail lower skin with plywood and added a Goldberg/Klett tail wheel assy with a 3/4" wheel.
Added tri stock to the horizontal stab.
Installed a well running MDS 48FS PRO. Way more than what is required, but this is the single change that makes it fun!

Good luck with yours!......Brian