[PlasmaKrab]

Relating size to armor or threat seems strange...

What about "soft" apcs like the LVTP-5 and -7, which are much larger and higher on their treads than many tanks?

Like Pyros said, it is much easier anmore sensible to discriminate directly between unit types. Once you know it is a MBT you engage it like an MBT. THe game already deals with that, by selecting ammo type according to target armor (or unit size, I don't know the rule for sure).

Anyway, size is used for detection. The biger your unit's "size" value, the more likely it is to be detected at closer ranges. That is why snipers have size=0, ATGM teams have higher values due to launch flash and dust cloud and so on, tanks and APCs have pretty much equal values, except for some low-profile recon vehicles. Boat have the highest.

AFAIK it also is used for hit probability, particularly when firing aimlessly at an hex (atrillery, cluster bombs...).

Things like dust raising, emgine smoke, overall visual stealth and I guess noise (?) are also integrated in the "size" rating.