...or let it be? I've read some opinions here--and have my own. I found this an interesting read:

(You need to Login or Register to view media files and links)

The answer is not all that simple to me. I have restored guns in my collection, and each was a pretty easy decision based on how bad they were. Each had various issues that made them nearly useless as they were, although not totally without value.
I found a #4 Ballard at a local show that had the barrel drilled out, and an old 3 groove Springfield barrel turned down as a liner. The outside was engraved with an electric engraver, ".30-30 Black Powder". Stocks were ruined from overtightening, and years of poor handling. Pretty easy decision to save the action and original buttplate, and have a new barrel installed, with new wood to make it like new condition. And at the purchase price of $200, I didn't end up in the hole when finished.
Same for a Hepburn that came my way. The receiver was pitted, no wood on it, and the barrel was a replacement. No brainer to finish the barrel, block the receiver, and have it engraved, then put new wood on it, and have everything cased and blued to finish. Another one that I felt I'm not upside down in.
But I also have old singles that have a lot of use (not abuse) and very little finish. I'd never dream of ever refinishing any of them, just because they are either too rare, or too honest to think of changing the way they look.
An old singleshot has to be pretty bad before I'd think of fixing it up. Mostly I get them functioning and make just enough repairs that they look unrestored, and shoot safely.

Just read this myself. Interesting read but I am pretty much in agreement with marlinguy. Can't think of a set of circumstances that would make me want to spend that kind of money to have someone like Turnbull do a total restoration on a gun even if I had the money to blow.

I am with the other guys on restore, if it is not a collector and useful to you to shoot, reasonable restoration is the way to go. 

Piece it out yourself to the gunsmith  finish and stock members on this forum gives a lot of pleasure with exactly what you want resulting. Turn key guys like Turnbull do a nice job, but seems to me it's like buying a shop restored 62 Corvette, nice if you have the money, not as much satisfaction as watching it all come to together

On the other hand I shoot re-creations, CPA' to be specific, and think they are good value too. Same for the US made Sharps High Walls and Ballard's.

Round it out our club matches would not be as well attended as they are without imports.

Pay your money take your choice, any single shot is worth having

Boats

Those are all great examples of guns I would consider NEED to be restored Mike! Anything that rare will command preimiums, but only if it's in the original configuration. Once the hacks have had at them, the value plummets. Bringing them back to original finish and configuration is preserving the history of that gun.
And bringing any family heirloom back to original so it can be returned to the owner, is hard to put a price on. Those situations fall outside the norm in my way of thinking, and are not dictated by cost or value.

Look at the results from almost any single shot match, lot of CPA's and always near the top of scores. Others good too, CPA's good as any.

It's a strong action not a lot of slop or vibration to cause trouble, and a good trigger.  Add a quality barrel & scope not much else needed to shoot well.

Boats

Boats

Each situation is unique. There is no rule of thumb.  you have to figure in the raw economics of value and cost and then the intangibles.
To me it might be a buggerd up old beater generic deer rifle.  but it it had been your great granddads and it had passed down through the family some sort of restoration might make sense.  One of my buddies had that done. the  cost was several x the book value of the rifle had it been in mint condition,  but he and the family are overjoyed.
  Now it it turned out the be one documented and owned by Clyde Barrow too, and your grand daddy was Bill Jordan's dad, a restoration by a recognized respected resto-shop to the way it looked when he had it, all properly documented makes sense.
  TV or web-cnn showed a old largeframe Colt DA revolver with the cutaway trigger guard  (a la' Fitz-special) that belonged to him and was in the ambush car.  No one in their right mind would have that frame and trigger-guard restored to factory configuration.

like I said no rule of thumb and lots of factors the consider

Boats, there were two Clyde Colts;   a 1911, and the "Fitz-Special" in his belt (and it may have been one of those big frame 45 DA revolvers  1917? or were those the S&Ws)  I assume the Auction-house knew what they had,  but the media-----oh well
if Bonnie hadn't had the "dick special" "strapped to her inner thigh"  wo-o-o-o-o-o   there'd probably have been no story