At the same time, I bet that in at least in 2/3 encounters in the LMA, the C205 will beat the P51D (can this be queried in the statistics?), just because of who tends to fly them.
Can it be queried? Of course it can! Stats pages, Plane Stats, click on the C205 kills and see how often it killed the P-51. Then go back, click on C205 deatsh and see how often it was shot down by P-51D. And if you do that for several tours, you get an overall picture.
But lucky you, I have already done that for every plane/GV combination possible, for all tours

For example, in all of 2011, the C.205 had 2,552 kills vs. 2,856 deaths against the D-Pony. So the Pony 'won' ~53% of the (conclusive) encounters.
To not entirely hijack this thread, here's my take on the OP:
My question: what is an 'attaboy'? Who is being targeted by this proposal, and what would it be good for? Because the only players that would be affected are the mass of new players, n00bs and other folks who are only occasionally capable of killing two planes in the P-51D and landing it.
For all that are able to regularly able to do that (which is the minority of players in any given tour) and getting their WTG's, it's quite easy to get over this threshhold. They will still get all the "attention".