I'm not sure about reliability - my 6th gen seems to eat stators like potato chips at a Super Bowl party. The 6th gen's is larger diameter, 4.52" vs 4.26" on the 5th gen, about 6.1% larger. IDK how much more power that translates in to. The yellow output wires for both measure 2.2mm outer diameter around the yellow insulation, so the same. Custom Rewind, below, put 2.9mm OD wire on my 6th gens, so a big improvement.
If anyone is wondering, Custom Rewind is still in business. I talked to them about a week ago. They did my 6th gen's 1st rewind and it was great. Cost now is $135 shipped back to you. Phone is 205-798-7282. 2014 Pratt Hwy, Birmingham, AL. 35214 If you leave a message they will eventually call you back. They will give you a custom length wire and whatever connector you specify. Probably should call them 1st before asking for the latter.