When the BMR said Mechs averaged between 10 and 12 meters, I strongly took them at their word, meaning only a handful of designs broke the mold.
So, that 14m Grasshopper is a little oversized. And, a lot of the light Mechs, if you follow that the cockpit actually fits in the head, are actually undersized. That, or the head is just part of an assembly that fits around the pilot's neurohelmet and the pilot sits down below the neck on a lot of light Mechs. the Jenner looks particularly uncomfortable.
I never had a problem with 10m tall light mechs that don't look distended, but proportional, because of all the different chassis materials once listed in the Tech Manuals, and the different armor manufacturers. It makes sense to me that Light Mechs might actually have a lot of air space under the armor, or that their Myomers are not as densely packed as a 100ton Atlas, let a lone a 55ton Shadow Hawk.
I've looked at the tank sculpts, too, and I can't believe that a J. Edgar, or a Pegasus hover, can actually properly fit a crew in the tank, not with an actual plenum chamber for air underneat the vehicle eating into the potential interior space. So, I've decided that some vehicles actually need to be larger than what that little chart shows. The Pegasus, Hunter, and J. Edgar minis I have got set aside for all the 1/450-1/500 scale stuff I've collected, like the BattleForce Scale mechs.
The APCs of any stripe, considering the tonnage they can carry and what that equates to as bodies according to the rules, means that the floating soap bar that is the Maxim, or the Heavy line of APCs, are actually the size of small houses, and I've relegated those miniatures to my Map-scale collection. This has inspired me to look at MWDA HQ vehicles and a few others as a starting point for modding/bashing some properly(ish) scaled Heavy-Hover, -Tracked, and -Wheeled figures for use with the more regularly sized Mech figures.
But, that's my take on it.
APCs in general have been a real contention for me because tonnage in guys can add up to a lot of volume real fast.