I love the Yak 9-T. When I first flew it I assumed the 37 mm would be as bad or worse than the German 30mm.
I recall exactly when my perception changed. I was flying base defense against GVs when a P-38 JABOED in and popped a few rounds at me as he screamed by. I was down to 2 shells left, so what the heck, I pulled nose up and fired at D 1.1. To my surprise, and no doubt the P-38's, his tail blew off!
That's when I read up on the weapon and discovered it has as high or higher muzzle velocity as the vaunted hizzookas. So I practiced with the .target command. Holy Cow, this thing shoots flat and far !
Since then I've had a blast with it. I make regular kills on unsuspecting bogies who blow by and quit manouvering when they think they are out of range at D800.
My best luck in killing Panzers comes with a high angle (near straight down) attack. This keeps them from knocking out your radiator, which happens constantly in a low level, low angle attack. But it also gets more outright kills, not just wounded panzers.
However the GV damage model is porked (how many threads are there on "I hit the Panzer 5 times with my Tiger and he survived"), so it's hard to be consistent killing Panzers with the Yak 9-T.
Against fighters, I have never once had to land more than 1 hit to take them out. As soon as I see the flash of the ping I turn away to assess the SA, because they always end in a kill. (I only fire the cannon in the Yak 9-T, so no confusing 12.7 mm mg hits.
It's not a multi kill wonder plane. It has lots of vices. But I sure have fun in it.