In the early 1920's the DRG(W) did a very extensive rehab on its narrow gauge lines, replacing old 40 lb rail with second hand heavier steel (mostly 70 lb). They also replaced many bridges with second hand former standard gauge bridges. This allowed heavier locomotives to run on much of the system. Before this upgrading K27's could only be found on Marshall Pass and between Chama and Cumbres where heavier rail had already been laid. After the rehab work, larger power could go many more places, but was still offlimits to some branches and the Gunnison - Cimarron mainline because of light bridge loadings.
A K28 only has 540 more lbs of TE over a K27. What the K28's brought in was a modern superheated engine that could pick up a train and run with it at speed. (we now have higher horsepower in addition the tractive effort) Very soon after the K28's arrived the motive power dept came up with plans to superheat the K27's, which made them a much better locomotive. While a K28 is much heavier, it carries a greater portion of its wieght on its pilot and trailer truck, which tends to make them more slippery than the smaller K-27's. I've heard stories from old-timers (no, not me) saying that in some cases a K27 would outpull a K28 when it came to a hard pull. I know I've had 463 do things that according to Tractive Effort vs. Tonnage figures it shouldn't be able to do.
Jerry Day needs to jump in about the inital assignment question, but I do belive the K28's started up in Salida. They were built as freight engines, but soon fell into the passenger role when the K36's and K37's came along. Remember when figuring out locomotive assginments, every locomotive must have a boiler wash once a month. It you allow a minimum of 3 days to do that, you just eliminated 1 locomotive every day. In addition, engines were held as protection power in case of trouble. Dorman's book shows a spare K28 in Chama in the late 30's.
