Paul, You are correct. I had 2 of that kit. Have sold both of them. Looks like I have 5 SLSF 40'ers, 4 other road 40'ers and several SLSF 50'ers. One of the SLSF 40'ers is modernized w/o a roof walk.
Admittedly, this is sort of stirring the pot. But when I see what are basically Athearn Blue Box cars with better paint jobs (still have molded on grabs, etc) selling for $35, and troop sleepers converted to box cars selling for $64, I wonder how we're ever going to get new people into the hobby. Most people would never consider buying something like that for a son or daughter and there's no value in it. The attached photos are cars I built (the red CB&Q grain box car I bought from David Gaines already assembled--the other four I built). I'm an average modeler--not terrible, but not great, either. It's just a matter of being willing to model, to take your time and patiently do some filing, sanding, fix the issues that the cars come with. In my case, I'm color blind, so my wife gets to (frequently) "advise" me on color choices. But that's part of the fun of it. My total outlay of cash on these five cars--including metal axles, kadee couplers, kadee brake wheels, etc., is about $35. Total. The SP and CB&Q auto boxcars are Intermountain that I built. Very few people want to assemble an Intermountain car, so you can get them dirt cheap. Look at the Rio Grande Automobile box car. It's definitely not anywhere near the standard of the modern $60 freight cars. But from 3 or 4 feet away--especially with it in a train, it's better than acceptable. The roof walk is pretty thin now; the stirrups don't look too bad; The bottom door guides have been worked on; etc., etc. They run great, they don't derail, parts don't fall off; and modeling is supposed to be what this is all about. Just my 2 cents worth on the state of the hobby...
Like any model hobby, it is possible to go to insane levels either detailing cars or buying $60-75 plastic freight cars. I've always tried to go to the Nth degree in building or detailing engines and cars. Now I'm old, have essential tremor and eyes could be better. My layout and most models gone and if I tried it over, I think I would still do the important things like that but put more effort into a good operating layout and enjoy operating. I've always been somewhat of a loner and never had an operating "crew", just me. Woulda, coulda shouda!
Don, your emphasis sounds exactly like what I have always prioritized...except that you are a spectacular modeler. Detail is great, as long is it doesn't render the model unusable. But modeling is fun part of where the details come from. And like you, if I had it to do over again, there would be more emphasis on a great operating layout. Mine runs fine, but it isn't that interesting and there are sections of the layout that could have been designed better. My layouts have also been single operator layouts. That's mostly due to space.