About the quality of the Buffalo......
First of all the guys who flew the Buffalo in combat had to combat a overwhelming amount of enemy planes. All of them ultralights!
Seeing your fellow squadronmates get shotdown and killed does something to you, so your opinion about your own mount gets negative.
About the armament.....
Quote from Jimmy Thach: Firepower is not a substitute for marksmanship
after the switch form 4 .50 (F4F-3) to 6 .50 (F4F-4)
In "Buffaloes over Singapore" is a quote from Kapitein Tideman (Dutch NEI-AF): "My view is that our drawback during the fighter actions was not an inferior aeroplane (the Brewster), but we had to few of them".
The Dutch pilots flew more often than not with half the fuelload and half the amount of ammo in the Buffalo.
In this configuration it could hold its own in combat with te Navy Type O.
But quantity was the deciding matter!
The Buffalo wasn't that bad, alltough obsolete at the time.
With the proper tactics it could hold its own.
The Finns showed that to be true. (26:1 kill ratio)
It all boils down to training and quantity.