While the #491 was considered the best-steaming of the K-37s, the #492 was considered a fairly good engine, and the #499 was considered the best of the K-37s, the #497 is largely considered one of the worst.
First, it's important to realize that individual steam locomotives tended to have "personalities". Even brand new engines of a same design, manufacturer and batch would perform slightly different. One might ride a little worse, or one might steam much nicer, or one might be impossible to get a clean stack on. There was enough variance in production that there were discernible differences. On the D&RGW narrow gauges, these engines were subjected to hard use and frequent wrecks and rebuildings, which further developed their personalities.
The K-37s, due to being built at D&RGW's Burnham shops from old standard gauge Consolidations, were always a bit kludged-together to begin with. The big boiler was cobbled onto a frame, and the frames on most 490s cracked right over the trailing truck. The engines had a Chambers throttle. They had two valve surfaces and when they leaked, they were hard to open and worked basically as an on-off switch. Spotting the tender at water tanks was a nightmare, and according to those who ran them, if you came up short, you'd have to put one foot on the backhead and jerk the throttle with both hands to get it open, then slam it shut and go for the brake lever. They were a bit trickier to fire than the K-36s, because they had a longer firebox that didn't slop down towards the front like a K-36, and the firebox door was rather low, likely a result of it's reuse from the standard-gauge Consolidation. You had to stoop low and really wind up to chuck the coal towards the front, very unpleasant if you were a taller fireman. The steam dome was a bit too low, and you had to balance between keeping the water high enough that it didn't uncover the crown sheet on the grades, but also not too high to where you would pump water into the cylinders.
The #497 was involved in a pretty spectacular smashup in 1960, when it was doubleheading with the #498 in the winter and they derailed. The #498 cleaned the doghouse right off the #497's tender and they both went down over an embankment. Both tenders were written off and the #498's pilot plow, running boards and cab roof still lay in the same spot 60 years later. The D&RGW rebuilt both the #497 and #498, surprising at that late date considering that they had already gotten rid of the #490 and parked a couple others, but there was a reason. The D&RGW was trying to get rid of the narrow gauge network and felt that if they had to rebuild two engines, they could present the expenses to the ICC and go "Look, these tough conditions cause us a lot of financial heartache."
The #497 was put back in service with the #490's tender (to this day there are more K-37s than tenders) and ran until the end of freight on the D&RGW narrow gauge line, and then ended up stored at Durango all through the D&RGW's stewardship of the Silverton Branch in the tourist era and then was passed on to the Durango & Silverton when they took over in 1981. In 1984, to address the power needs of the operation, which was mostly making do with the old K-28s, they got the #497 running again. Worth noting that there was never an evaluation to pick the best engine. The #497 was restored to service by the D&S in Durango essentially because it was already there when Bradshaw bought the line. The #497 was left in Durango, along with all the empty freight cars it could have added to the last eastbound train because the only available division engineer to run it as the second engine laid off to attend his Mother's birthday party. The D&RGW couldn't reach agreement with the Union on deadhead wages to bus an engine crew over from Alamosa, so everything was left. The #497 and the #481 were both there and deemed "stored serviceable". D&S had fired up the #481 in '81 and run it to Silverton, the first K-36 to ever go to Silverton, and figured that the K-37s were basically the same engine and the #497 should work just fine.
According to those who ran it, the #497 was never quite right. It rode smoother than the K-36s but it had some serious tracking issues. It was very stiff, and was notorious for kicking curves out of alignment and on both roads, it was later traded to the Cumbres & Toltec, it actually broke foot-long sections of rail out of the track in curves, and according to one engineer, once on soggy track, he literally saw the curve start to kink 20 feet ahead of the engine when the ground was wet. Some of that was due to a homebuilt lateral motion device on the lead drive axle that never worked right. The trailing truck also had some accident damage that wasn't fully resolved, and it always had issues and it had the spring equalizers come apart on it out on the road a couple times. There may have been some issues with the lead truck as well, since C&T swapped the #497s with the #492s and that helped some of the tracking issues, but it was still a hard machine on the road bed. The injectors were always problematic and after the water level in the tender dropped below 4000 gallons, they overheated and would not start to fire. The throttle had the usual issues, and ended up getting a redesign to solve some of them.
In the end, D&S traded off the #497 to Cumbres & Toltec for K-36 #482. D&S had also had the #493, #498, and #499 trucked in during the early 80s, anticipating a future return to service, but assumed that the #497's issues were endemic to the K-37 design as a whole. Once they traded off the #497, they also got rid of the #499 (ironically considered the best of the K-37s) and parked the #498 and #493 outside and left them there. It wasn't until in recent years that they realized that the K-37s would work fine and fired up the #493. The #497, after going to C&T in '91 ran until '02, although they were never very pleased with it either and it's been parked since then. They looked at restoring it, but chose the #492 instead, partially because of the new boiler but also because it doesn't have the accident damage that the #497 has as well.