I have some E7s and F units and they run real smooth and slow. They are a little tight as delivered and need some breaking in.
this is a very nice drive system aimed at scale speeds and operations as compared to the "china block" 2 motor drives which in my experience run like slot cars and have jerky starts and stops. the 2 motor truck mount drives have the advantage of being able to handle much tighter curves in most cases depending on the truck detail. I think the speed disadvantage has two causes: First they importers/builders use very cheap motors which have very weak low end torque so they have to run at higher speeds to get any power. Second the gearing is set up for higher speeds because the importers/builders think that is what the 3 rail market wants. A 3rd negative on them is that to accomodate the gearing on one side, the truck side frames tend to be set way too wide on the trucks. Visually the truck sideframes should be tucked pretty far under frame, not parallel to it.
