I've got the guillotine type cutters, not the 1 size fits all screw type, you need 1 for each size of pipe, I have 1 for 15mm and 1 for 22mm, only really ever use the 15 to be fair, and it's usually on rad valves. Your right though if the pipes too distorted I just cut it back but if it's only a little indent a fresh olive usually seals up fine. They look like my old monument cutters but I think they're Nerrad? If your thinking of giving me a try Kay-jay start with the 15mm, you'd get a lot more use out of it.
And plumbstar Tom your right, I had a few drinks last night that are still disagreeing with me now!