Southern Mantis (Cho Gar / Chu Gar / Chow Gar) are indeed all from the Hakka families of southern arts in general. There is absolutely no similarity between northern and southern! Just about everything outside of Nian (sticking) is different. I am not sure what they call it in Chow Gar, but they do focus a lot on stickng types of energy.
And it is also true they are very similar in power generation (not looks mind you) with Bak Mei, Wing CHun, and White Crane. The Mantis guys do a lot of (TOTALLY THEIR TERMINOLOGY) swallowing and spitting energy too. The swallowing is an absorption of your opponents incoming attack / energy. Spitting is where you absorb your opponents energy and redirect it back at them.
As for one looking more like an insect than another.....okay, whatever. I do not try to emulate the insect, rather I try to become his fighting instinct and demeanor. I am too **** big to be an insect.

Cheers
Jake