Whilst a OO gauge s160 sounds good, reality is for UK modellers, it's a very limited number of liveries (black or grey) to represent a 4 year wartime period in the UK.
For post war modellers, theres only one, periodically working the LMR only, for 5 years, between 1952-57.
The s160 was unknown to the UK enthusiast for 33 years until 5820 came to Keighley in 1977, followed by Greek/Hungarian/Polish and Chinese imports in the late 80's/90s.
In preservation theres 5 preserved ones that have worked in the U.K. so far (5820 in grey, 6046/5197 in a very nice, but maybe not accurate Black, 2253 in usatc Black and 3278 which was restored in LMR blue as WD 701.
Its said the 0-6-0 s100 was a run of 6000 models over 10 liveries / variants, covering a period of 1942-2017.
Assuming all five of the preserved ones were modelled (which gives 4 liveries, 2 of which are preservation only) then it's down to different running numbers and duplication to sell enough of the rest.
How many people would buy 2,3,4 s160's ? (Given 2 together in the U.K. has only happened once in the last 72 years), especially considering the latest one is £340, discounted you can get for £300 and such a OO gauge one is likely to be the same.
Would there be enough demand for a fictional 95820 in BR black as was for a few weeks a few years ago ?, how about both LMR variants ..WD700 in the 50's to go with the MHR's 1980/90s WD701 ?
You could try PKP livery as 2253 ran in this at the NYMR ?, but for all the European, Asia, US liveries that market will surely go to Rocos new s160 which is HO and suited to those modellers.
The UK only has so many s160's because they were cheap, fitted the loading gauge and in working order when acquired by the various preserved lines, 3 more have yet to run in the U.K, though 2 of these are very unlikely), that there's more working s160's than A4's right now is down to coincidence & economics, not popularity, just like the 8 or so PKP ferrum's imported which have no U.K. History.
Several times I've heard rumour of an s160 going mainline! Even as far as a london suburbs railtour mentioned, but since that climate changed I suspect that's more of a dream than reality now, but even then would it sell 6000 models ?
Now to myself, I bought the one above, was suitably impressed to buy the black one too, but as I have an international element to my collection (I model DB/PKP too) I'm happy to have them in different worlds of my layout.. much as I would like, at £300 I can't bring myself to put isoprop to the "US zone Osterreich" lettering on the tender to make it a pure USATC black one, I do have US numbers too..
Personally in HO it's not too bad against OO, I'll post some comparisons in the s160 thread, i have a few flieschmann Bulleids in HO to go with it. I have two HO s100's too, they live separate to my OO ones, but were bought based on acceptance there wasn't a OO one, so never say never eh ?, but until then I'm quite happy to mix and match.