So, basically a K-4 with the 20 mil option, why not? Because we have to many 109's already? Maybe i have a biased opinion because I'm a big fan of the 109, but in my honest opinion it doesn't hurt the game if we have add a slightly different 109 then what we have already.
Correct me if I'm wrong, but it looks like the G-10 only needs a small modification to that of the 109K. That looks far less work compared to building new planes from scratch (D4Y, A6M, G4M, P1Y, Ki-43, Ki-21 as previously been mentioned).
In other words: Make a small adjustment to the bubbles on the nose, give it a 20 mil option and a slightly worse engine and your done!
My 20 cents.