I never had any wiggles with my D606 fronts, nor really any other knobby front tire... or maybe I'm just numb to it. Well, to be fair the non DOT IRC VE-39 I ran for a few thousand miles walked around a bit at speed, but nothing bad enough to ever cause concern. Speed wobbles are as much setup as tire.
I did find that the D606 front didn't wear all that well and would cup fairly badly in as little as 2000-3000 miles, or about half of what I got out of a rear. YMMV... Only ridden an MT21 front once, and briefly, and liked it well enough to be willing to try it as an alternative to the D606 front.