but I was wondering tonight why is there not a dedicated core of good P51 sticks?
There used to be. After flying L/W for a couple of years, I was lucky enough to get to join the 13th TAS about ten years ago. I was the "youngster" in the squad, most of the guys being 20 or more years older than me at the time, Rude, Toad, OzKansas (RIP), so many great sticks in that squad. It seemed every night I logged in I had 8 or more squaddies as wingmen back then. I'd say half of my time in the air in that squad was spent with my flaps down more than one notch, we were a P51 squad that didn't take bases or bomb, but FOUGHT, and most of my good memories are of low level twisting fights in the "old" P51 model that turned pretty well, had tons of ammo, and was deadly when used with 4 or 5 friends against mobs of opponents.
As for nowadays, BigR and Pand, as well as others mentioned are always guaranteed to give an entertaining fight, as opposed to a lengthy linear pursuit, but as most others have commented, the ratio is what it is, as the P51 is lets face it, the most "popular" or known fighter of the war, and new players will automatically gravitate towards it, and then stick with it due to its easy mode attributes.