[quote=@Crimmy]
<Snipped quote by Aristo>

Is there a hard limit you have for how big a mech can get?

6m seems to be the general size, but what about a 9m mech?
[/quote]

I'd like to top it off at around 6.1 meters, or 20 feet. Otherwise, they start to get too high-profile and easy to spot. The general design philosophy is being mobile and elusive. 
Frames fall between infantry and IFVs - nimble and versatile, bringing a variety of weapons and capabilities to the field.