I found that Inverted flat spins will recover spontaneously. I.e., just let go of the sticks and airplane will spontaneously recover.

Upright flat spins can be disastrous and may be impossible to pull out of. I've been able to pull out of Upright flat spins with opposite ailerons. It was kinda scary.

I've never had thrust vectoring, but I would assume that would make it much easier. When you are Upright, you don't have your rudder in the wind to stop the flatspin.

If you give opposite aileron and opposite vectoring with increasing throttle would probably pull you right out of an upright flat spin.

Here's a pic of some Upright flat spins that puckered me right up.



Try them up high and see how it goes.