I"m not sure, switching between the two sizes. I've never played a game on my big board. I think my kings are 4"/squares 1.75"
But you still have the advantage of looking at a physical board. I' have to be careful on the peg, I have to make sure I'm not missing anything that I wouldn't in 2d.
Also, bear in mind in not that great a player. The peg is a good set up, other's experiences may differ. My peg connection seems to benefit from my wearing leopard-print mini-skirts.
I am just wondering: If you play your training games on the Peg, and use it to set up puzzles, training etc...when you play at a tournament, or local chess club, where the boards are a fair bit bigger. Do you find any problems going back and forth between the board sizes?