John, understand and appreciate your perspective. But I'm a bit more lenient in what I decide is "good enough" as opposed to what it too far beyond the prototype for me to consider. I was aware the aft lighting package was "missing," though not the wheel brake issue that you cite. But even if I had known of that, I would have still bought #7399.
On the other hand, years ago MTH did the SP SD40-2 in the "Daylight" scheme. I knew the prototype was a SD40, not -2, and held off buying for a long time...that front platform was just too long. But I saw the PS-1 unit at a good price at the Great Steam Festival in Michigan in June '09, and bought it. I knew my LHS (EngineHouse Hobbies, Gaithersburg, MD) could covert it to PS-2, but while the colors were right (except, IMO, the grey was too light), the lettering was wrong, and that was an "error" I was unwilling to live with. Unlike #7300, the SD40 had "Southern" stacked atop "Pacific." So I got a set of decals from MicroScale, removed the old lettering, repainted the "Daylight" red, re-lettered the unit, and then had it converted to PS-2. So I drew the line at lettering format, but let other "errors" ride.
It's just like my Powder River coal trains. I'm building two 16-car trains. Atlas 100T trucks and Kadees do wonders on those MTH "Coalporters." One will be loaded with real PR coal I got from the Thunder Basin in '06, and one will be MT. 16 cars on a unit coal train--who am I kidding!!! But on CONUS Lines it looks big, really big, over 25 feet in length, spanning several of my scenic vignettes. And with two powered units up front...and one powered and one non-powered serving as helpers or DPUs, it "sounds" BIG.
The late John Armstrong once observed that after the engine and about a half dozen or so cars go by, most viewers lose interest and wait for the caboose and helpers. I've had enough open houses at CONUS Lines to confirm John's observation. Even my 18 car sugar beet train, which is the heaviest and longest freight I run, with four powered engines, garners attention at the beginning...and with those SP tunnel motors pushing hard at the rear. The intervening 8-10 cars are just "white noise."
So I'll run #7391 on the point of an SP freight, and most of my audience, myself included, will be satisfied that it is "good enough." But I certainly appreciate your affinity for accuracy. And I do wish we had the options in O that I used to pursue ardently in HO to get detail parts, etc., to render our models more accurately.
But frankly, for now, I just revel in the quality of product we have in O as compared to 20 years ago...and am a happy camper!