Well, tour 150 is nearly over and I thought that I'd check my A-20 stats...
74 kills, 4 deaths.
Against aircraft, 39 kills, 1 death. I believe the one death resulted from a collision with a P-51. All air to air kills were in defense of an airfield (all kills, both air and ground resulted from defending a base).
A6M5b: 1
B-17G: 3
B-24J: 1
Bf 109F-4: 1
Bf 109G-14: 1
Brewster B-239: 1
C-47A: 1
F4U-1: 1
F4U-1A: 2
F4U-1D: 2
F6F-5 : 5
La-7: 2
Lancaster III: 2
N1K2: 5
P-47N: 1
P-51D: 4
SeaFire: 2
Spitfire Mk IX: 2
Spitfire Mk VIII: 2
I'm usually below 5k, frequently on the deck.
So yeah, if flown intelligently, the A-20 is a potent adversary. IMHO, it's single greatest advantage is that few opposing pilots take it seriously... At least until they find themselves in the tower.