Spectacular catalog - are they really scale?

They are scale or very close to it, and no, some of the details aren't accurate such as the bottom of the boilers and such.  If that bothered me at all I'd be in two-rail modeling, but when I looked at that eight years ago before getting into O from N gauge, I realized you give up something either way - 2 or 3-rail, and i decided 3 was for me.

Two rail gives up the wider range of offerings and better running and easier handling of three-rail locos for near-complete fidelity to prototypes: many of them are exquisitely beautiful models (I have a few, not many though) but delicate and frankly, not the greatest runners for daily use.  Legacy and Premier offerings are scale or close enough for my tastes, run so well and so durably, and I like them because they are easier and safer to handle than most brass, and there is that bigger, less expensive selection available.  In fact in a few rare cases, I prefer the Lionel and MTH to true scale actualy - I have the 3rd Rail ATSF 2929 Northern but its on display in my office: on my layout I run a hybrid I prefer instead - the old (1990s) MTH scale body with Legacy chassis and electronics and sound,  because it looks better: MTH used their scale 5012 body for it which makes it two feet longer than scale - that length gives it even better proportions so it looks better, and that is, first and foremost, what I go on. 

BTW - the windows on the E units really do stink, but its not really the windows but the way the body casting around the inside of window frames is cast into the body that has to be fixed.  As a result it is not that easy to fix yourself (I'm doing so now): a lot of intricate cutting and trimming of the new windows is called for.  

Yes, "our" 3-rail scale models are indeed made to 1:48. The center rail is just a circuitry

convention at this level. Are there fudged measurements, and things done to make the

model actually work? Sure - just like in all other model railroading formats. 

My one continuing complaint with large, 3ROS steamers are the typically WAY too small

wheels on leading 4-wheel trucks. Lionel is a worse offender than MTH, even on 072 

models of the same prototype (see UP-type 4-6-6-4 from both companies), and I have

complained here and elsewhere before: if you are going to charge hundreds or even thousands of dollars for a 4-8-4, can we not at least have a second pilot truck included

for those of us with big curves - or at least a pilot truck with extra wheel/axle sets

and a simple retainer plate on the leading truck?

Lionel did this (extra truck) with the 5344/Vanderbilt tender Hudson - and the scale wheel truck has been operating on my loco since day one.

True O scale takes into consideration the size of everything on a model train engine not just the body.  All accessories, details, window bar widths, light,whistle, couplers wheels, truck, and wheel flanges must be sized correctly. As such Lionel has never made a true scale engine, excepting maybe, the original 5244. The newer "scale Hudsons" are way off scale. All of Lionels and MTH products are  "semi-scale".  That's close enough to look good but will never satisfy the diehard O scale purist who migrates towards the O scale brass engines. I sat in among a group of O scale modelers ( commonly called rivet counters) and they all frowned on what we refer to a scale. One told me to measure the window dividers on the scale Hudson and see if that was sized to scale.

that is by far the most important criteria to me.  The only other thing I want in my "scale" models is that they are all close enough to 1:48 that I can compare their size and features side by side: and I will not be comparing the width of window dividers either, but the size of drivers, the headroom in cabs, and such that I think Lionel and MTH get close enough for me. 

Frankly, if a scale model has to have everything correct then there is no such thing as a scale model.  I was in the cab of an ATSF Northern in 1954 and remember being very impressed that the throttle lever was wrapped with black "friction tape" just like my Dad wrapped the handles of his hammers with at home.  No one has ever modeled that in O-gauge, I'm sure. Everyone has to make up their own mind what they want and then work to get it: but the quest for the perfectly accurate model is impossible, unless you stick to 1:1 scale.