If it's for your own project, go try it. If it works, then fine. If it dies, then no harms done (unless it's your own personal Pacemaker you're modifying!). I'm kinda boring - I almost never build things to exceed manufacturers component specs - it's a sure road to disaster.

If it's a marketable product for sale, DON'T. It's bad practice to run at (or beyond) maximum ratings (apart from the fact that you'll almost certainly invalidate your Public Liability Insurance!).

If you buy a car sold as capable of 160mph, then you would like to know that it'll do that all day long regardless of ambient conditions. Would you be happy knowing that when you reach 160mph it's within 0.1% of blowing it's head (or worse)?

Kiddies (and techies who should know better) like to tinker and overclock their PC's for example... then halfway through a major piece of work it has a cardiac and they end up crying into their coffee about the f****** PC and how much work they've lost. Go down this road and it's your own fault if things go wrong or you end up wasting heaps of time chasing your own tail. I'm not saying it doesn't work, but I am saying you are skating on thin ice.

Just as my Pentium III 1200 runs quietly at 1287 Mhz ...
Hmmm... a 4MHz PIC running at 8MHz could be compared to your P3-1200 runing at 2400MHz... might have some reliability issues here...