I have a lip mount similar to the K400 (it's the MFJ version) on my Kia Soul. It's on the top of the right passenger door, and holds a dualband (2m/440) VHF antenna. It works fine, but the one I have doesn't look strong enough for an ATAS ... maybe it IS strong enough but I'd be hesitant to try it.
The Diamond K400 is more than strong enough. I have a Little Tarheel II with a 72" whip on mine. When someone stole my last Tarheel II from my car, the steel on the hatch lid gave up before the antenna parted company. I got the antenna back, still with the Tarheel attached and the bracket hadn't moved at all. They'd used so much force to remove it they'd bent the clamp part of the K400 and slightly bent the tube on the Tarheel but the swivelly twisty parts hadn't budged an inch and were in exactly the same place they were when I'd tightened them up.