Well, it depends, and to each his own.
First, I don’t see how anyone can honestly claim that a flint made gun could have been used as a percussion for a longer period of time, than as original flint. The flint period ran for more than 100 years, whereas the percussion period was a mere 30 years. And for Kentucky style long barrel rifles, their use was pretty well done and gone by about 1850, so their percussion use would have been closer to only 20 years because better, new, shorter, lighter and inexpensive guns were available by then. Yeah, I know, some were used longer, but most were tucked away in a barn or closet by then.
Most of the wear and tear on the wood, metal, and barrel breech on the old flinters aren’t from long honest use as a percussion, but instead, lack of care, from not cleaning the crud from the percussion caps off the gun. That’s probably the same period of use when most of the silver inlays vanished as well. Also, anyone that has been around these old guns for some time will come to realize that most of the damage we see today, was done to the gun long after its primary time of use, as a flint. Take out the sentimentality, and see what you have left for illustrious history!
That’s not to say there’s no reason to leave it as is. Some guns were well kept, used, and cared for, for many long years by many generations.
Most weren’t.
Most were tossed in a corner, forgotten, neglected, and left to the ravages of time.
So I’d asked first which of these scenario’s fits your gun, and go from there.
If you do decide to reconvert it, as mentioned above, have it done well! And realize that a good job of reconversion isn’t going to be inexpensive. Besides doing the lock work, there’s going to need to be work done on the barrel as well. A lot of guns had the barrel cut back at the breech when percussed, and any good reconversion would require adding that missing bit back to the barrel, and that in turn requires adding a bit of wood to the muzzle and addressing the underlugs and fastening to the stock.
Also, a lot of rifles had 6 inches or so whacked off the muzzle end of the barrel too, and not replacing that after reconverting back to flint, would, well, really look strange.
And doing a half-assed cheap job would be an injustice to the rifle, so to do, or not to do, can be a difficult and expensive decision.
There’s some guys here that have, and can do, an excellent job of reconversion with no sign of work either inside or out on the gun, short of an x-ray.
No mater what you decide, let’s see some pictures of your rifle!
And as JV mentioned, be sure your rifle was originally a flint. If you're not sure how to determine that, just ask.
John