It's all relative I guess. While the FG17 would odd's on do just fine, when your talking $330 vs $500 for the FG21, I wonder if the extra $80 the FG17 would cost over the DLE20 just to get a specific sound, even when it's still not a scale sound, to (personally) be a waste of money for a a motor that is less powerful.
The only thing to worry about is how heavy that new P47 would be. My H9 P51 which is done with almost the same scale level is a heavy pig, which was part of the reason I went with the DLE20 - well that (power), cost, running cost, flight times etc etc. NB, I just checked their website, and at a listed 11.5lb, she is just like my H9 P51 - ie she's FAT! (LOL)
At the end of the day you'll get what you want to get, and if it works, it will be the right decision regardless of what I or anyone else may have done in your shoes. All the best!!