Making them last "forever"

Many moons ago this board had discussions about how long the D&S and C&TS engines can last, with opinions ranging from with proper maintenance and rebuilding they can last forever, to the need to build replicas soon. Then there is the always interesting argument over how do you use a locomotive and "preserve" it at the same time.
The 476 may provide us with something of a test case for some of this.
Rick Steele noted in an earlier post the importance of establishing a regime of fixing things properly, with regard to some of the problems Ed and Bob are now finding with the 497. And this means doing things BETTER than the big railroads did, at least in the last days of steam, because a lot of preserved steam shows signs of some pretty shoddy workmanship. Some of the boiler patchs I've heard about make one wonder how they survived at all.
This is one of the reasons that I feel strongly that operation of the C&TS by a non-profit is the way to go. The D&S and C&TS are unique, in that they are not only museums (I'll give the D&S the benefit of the doubt on that), but operating railroads that need to run trains every day, get the hogs out of the house on time, work 'em hard and put 'em away wet. They have a lot of the pressures of the old big railroads, to just get it f