Our Bf109G-10 is a hypothetical G-10 equipped with an engine that would bring out the best possible performance for 109s of these series - bringing it up on par with the K-4.
Therefore, to tell you the truth, our G-10 is a sort of a "what if" plane. There's no evidence of any sort to back up the existence of a Bf109G-10 performing as it does in AH.
If Allied fans would complain "it's unrealistic", the Luftwaffe fans really can't say much, because it is...

Therefore, with maybe the exception of little better roll rates and climb, if a K-4 is introduced, it would perform identical to the G-10.
My suggestion is, remodel the G-10 into a K-4, and give us a G-14 to fill the gap between the early G-6 and the K-4(formerly G-10).