I'm not talking about a straight-up vertical stall. I'm talking about flying straight and level at about 130 knots, then pulling stick back sharply and maybe adding a little rudder. The plane begins to fall straight down. This falling bit continues even after any spinning is halted by stall/spin recovery techniques, and the fall may occur in various attitudes such as flat/level, tail first, tilted one wing down, etc.
As for "squirming around for 5 seconds", I have repeated this test from 500, 1000, 2000, 5000, and 10,000 ft and with various fuel loads, 3 different "real world" stall/spin recovery techniques, the spin recovery technique that is hard-coded into AH1, dropping gear/flaps, and several other techniques, and none seem to work.
Real life physics do not cause most conventinally configured, dynamically stable aircraft (like those in use during WWII) to fall into a "falling leaf" deep stall straight down.
If it's a feature and not a bug, then I suppose people better not stall the spit5 in the game.