I have a full ghillie (pants+jacket), with front covered.
it is IMPOSSIBLE to crawl in it.
if I crawl for more then 3 feet it looks like I'm having an epileptic seizure- twisting and turning to free myself from branches, tossing the gun in the process..
But still, it provides the best concealment possible, and I opted for a full suite with front cover so I can shoot while crouching. (when prone, LOS is mostly obstructed by foliage.)
If you want to move fast, and just be a bit harder to spot from a known position, like when you set up an ambush for the enemy thats coming from a known direction, I'd say go with a head cover and a waist long poncho.
But remember that an enemy coming from behind you will spot you.
(a pair of legs sticking out from a bush..

)