As long as it's done WELL, it shouldn't (J. J. Perodeau does a really good job with these). That said, for that gun, I'd probably want it done so that I could save the old pad and put it back on in the event that a potential purchaser wanted it that way. If the holes are different, then I'd probably go with the Silver's. Given good fit and the stock design that a British gun like that will have, for me, the Silver's is fine up through .450/.470 class guns, and I don't really feel the need for a decel, nor do I notice the difference. It just depends on the individual. You may need a softer pad.

What does this gun weigh?