Comfortable? When I have the nuts and my opponent has to hit runner runner or is drawing dead. Like when I have quads or a straight flush. Or when he's very short stacked.

I don't feel "comfortable" calling an all-in with the current nuts if they are easily out drawn, like with a straight or top set if there's a flush draw out. I do it, but I don't feel comfortable.

I'd say the question is a wee bit too abstract to get a good answer.