I seem to have found a devilsaur on the isle of Thunder that doesn't make stompy noises either. It's the blue one that hangs out with that Zandalari war-leader mob with something like 5.5 million health. I tamed it to try and get it out of the way, to make one less creature I was attempting to kite when I pulled him, and after all the chaos (and the spirit run), I noticed that the devilsaur was A) - rather pitifully grateful, according to my PetEmote and B ) - didn't make stomp noises.
He wound up with a name, so it looks like I'll be keeping Luckydo in addition to Junior, the other devilsaur I had already.
