Well, I wouldn't put the T-34 in the same class as most "warbirds".

In fact, the T-34 looks a lot more like a 4* with trike gear than anything. It's probibly more stable than a even a 4*.

The wing is quite big, lots of wing area, and no taper. The weight puts it pretty close to most trainers, or maybe even a little lighter.

So, sure, I don't see any reason why you couldn't use it as a basic trainer. I've used worse.

The big thing is that because of the wing shape (no taper) and light wingloading, it's going to land nice and slow and not have the nasty tip-stalling problems "warbirds" are normally known for.

The only down side that I could see, and I'm guessing here, is that many trainers are over-built to take the most common minor crashes in stride. Things like lots of extra ply in the fuse, extra sheeting on the outter bays of the wing, stronger wing spars than really necessary, etc. I don't know if the T-34 is built that tough or not. But with a good instructor, some caution and some luck, it would be a non-issue.

Some students really do need a trainer that can really slow way down and be stuper-stable. For them, the T-34 might not be a good idea. But from what I see based on the specs of the plane and so on, I see no reason an average student coudln't use it to learn on.