I love my 1:58 K-line 2-6-6-6; it is actually a "scale" model, while the RK is a compressed
model, even though it is larger. It is also a nice piece; I don't own one.
The K-line detailing is generally crisper and nicer.
My TMCC/Cruise/RS K-line Allegheny runs and sounds very nice; it has run side-by-side
with a Lionel scale piece on a large club layout. The Lionel was "nicer", but the K-line
looked/acted nice enough that I wasn't wanting to trade it in.
The K-line version, loco and tender, is about the same length as the Lionel 1:48 USRA
2-6-6-2 Mallet, loco and tender, so it is a substantial piece of equipment.
I just wish that the firebox sides could have hung down much lower (like the real one),
but those tight curves would be out for many, I guess.