I'm from Topeka and my father, grandfather, and great-grandfather were all ATSF engineers. Prototype isn't an option.
Despite the ATSF having the most trackage in the US, it tends to be No. 5 on the steam popularity list behind Southern Pacific, Pennsylvania, Union Pacific, and New York Central. ATSF was the most progressive railroad in a sense - it shifted to oil burning earlier - and to diesel earlier - so it's popularity is more tied to the Warbonnet diesels like the E8, F3, and F7 - I'd venture to guess more ATSF F3s have been sold across scales than any other locomotive.
Other than O - which ATSF gets pretty fair steam treatment from via MTH / Sunset - there's not much out there in other scales either. There's zero 1:32 / 1:29 accurate steam options - it's all SP / UP for the most part. HO is just seeing some plastic ATSF specific steamers from BLI - Northern and Mikado - though reviews of them are mixed - electronics issues. Most HO options are 40 year old brass or USRA generic models (of which the ATSF had none).
Based on what I've seen - there's basically 4 accurate steam models:
American Models Northern - ATSF was the base. 2 road numbers (but one can always add more).
S-Helper Consolidation - Baldwin base model - acceptable for ATSF
River Raisin B&M Berkshire - ATSF bought 7 in 1943.
Lionel Y-3: ATSF bought in 1945 and sold in 1947
Frustrating right? Try being an Erie steam fan like me ! ;-) 1 correct engine done in S and it is mediocre at best. The only Erie Berkshire done in the past 20 years was in O scale by Sunset about 8 years ago or so and good luck finding one. How about the beautiful K5 Pacific? Boo Rim built exquisite examples in HO a few years ago. Good luck in other scales though unless you go back to 50yr old Max Gray O scale models...
As I said, and I’m taking my own advice here, stay with S because you love the size or move to a scale that better covers your prototype.