An average close range FoF will kill 10 of the space clown. And we are not taking any ML hit into account. Of course they can easily find cover, but they don't need cover since they already have 5+ invul. So meh. And anyaway Banshee and Scorpion already massacre our firewires, so why bother ? As a foot note, Gun Drones are good to use against them. They can make some serious damages, fire from 13 inches so that you can spot them and aren't in range to be shot at, and can approach the harlies from the side so that going after them means going away from your army. And even if they are caught, they aren't worth crap so you don't care. Ho yes, and Kroot can slaughter them if they counter charge.
So yes they are (a bit) dangerous, but I'm still more worried about the auto glancing weapon platform, the mighty Falcon, the nastier-than-ever Fire Prime, and the Wraith lord.
Soji, as always at your service