Most epic transport are relatively reasonably scaled actually. Real life transport are not that big, a m113 is rhino sized and carry more than 10 men. Keep in mind that the proportion of a miniature humanoid are altered a lot to be produced and painted (e.g. they typically have hands as big as their head). This is true for 28mm, even more for 6mm tanks.
A 4cm tank in 6mm scale (=1/300) would be 12m long. a real life M1 abrams is 8m long. 12m would be more like the size of a bus IRL... a M113 is about 1.6cm in 1/300, and modern IFVs (
this one or
this one) are a bit more than 7.5m, which would translate as 2.5cm at 1/300. These vehicles transport 10 men squads on average, plus 2 or 3 crews.
Most of the Epic line IS true scale, except the Titans and planes, and some infantry models are a bit too big. It is a common misconception but a misconception nonetheless that 40K infantry transports are "underscaled". They are based on RL transports. The impression stems mostly of the rigidity of the figures and their otherworldly proportions.
To a degree, I hate that warengines tended to be dwarfed by ordinary planes in the FW line, And I'd hates IFVs to dwarfs my warengines in yours. I Like the scale to be consistent, but i think the things to correct are the infantry (which you do fine) and the warengines, not the vehicles.
I might be alone on this, but if you can fit 10 miniatures in it, it probably means that it could actually fit twice the amount of troops. I'd really prefer a vehicle scaled on par with real world vehicles.
So, to summarize : I love true scale, but i don't think it always means "bigger than GW models" when it comes to vehicles, so I'd like these models to be smaller.