Dogbone or T either way it is accomolishing the same thing. I prefer the look of the T over the dig one, but that’s just my preference.
You are correct about the minimum radius, and your 0.07 number is also correct to get the minimum overcut possible for a 1/4" cutter. I use the built in corner treatments in Carbide Create, where you can just select digbone or tee and then input the radius you want to use.
You can absolutely use a small chisel or file to square up the corners, I prefer to let the machine do that sort of work, but the tradeoff is of course the design aesthetic. Not everyone is into that sort of look.
Another option is to use overcut corners, but do them blind, so the joints aren’t noticeable from the outside.