No more so than the Yak-9, and they aren't too common. IMO, its mostly because the Yak doesn't offer extermes of preformance in any one area.
It can do a bit of everything with reasonable preformance, but that leaves it vulnerable to any plane on the extreme end of the spectrum.
109K and 190D will BnZ/slash attack this thing to death, or will try to entice him into a looping match, which they know they have an edge in.
Spits and Niki's will out turn it, and tear it to shreads.
P-47's and P-51's will dive on it from 10k.
IMO, its vulnerable to extremes in preformance, which is why it is relativly rare. The same can be said of the C205, the La-5, etc. Both are deadly aircraft when they get even 1/2 a chance, but they don't usually see that chance against an equal opponent in a high preformance aircraft.
you dont see the yaks much because of the ammo loadout. if you have to fight the yak9us fight your in for a great fight in any ride.
the ammo load out is not ideal for bnz or vulching. you have to win the fight using the yak's advatages against the other plane sets.
