Would leftovers of this recipe keep/reheat well?

You can add a little milk before heating it, but a lot of taste will be gone and it will be rather greasy.
I second nutcakes, carbonara is much better cold than reheated.

Yep, nutcakes, well put!

It doesn't really. You can do it for yourself but it will likely turn a little greasy, I wouldn't serve it to guests except freshly made. I make just enough that I need and if I have carbonara leftover I eat it cold. I've not made this particular recipe.