Indeed, the most mysterious enemy.
I'm no Commando expert but I definitely noticed that the "Rollers" health is unreliable. I try to dash them as much as I can... only way to be 100% they'll be destroyed when you expect them to.
Now, I may be imagining things but I find that the closer to the house they are, the more health they have. Again, I could be delusional about that but they really seem to go down easy whenever I shoot them shortly after they spawned.
Formerly known as Cobra_Qc on Housemarque forums and on PSN