Hi Phestus,
Well, I can’t say that I’ve ever really heard anyone say that their screen is too big to work on!
I had or rather have, just not here, a 22” second monitor which I can just about get an A3 painting to display life size on. As A3 is my preferred print size being able to see the entire painting on screen life size is very useful.
So I would say that if you have the desk space and your finances can run to the 22” screen tablet, then get that.