At boat speeds yes, hiway no.
On the soft tops they actually have a warning sewn in for a 'never exceed speed' of 40mph (or so).
The snaps are strong but not for a 70mph gust. If one pops loose the whole thing will go, just like a hurricane.
BTW, i've been using lip-balm sticks for snaps. Works awesome. (not ecolips :wink: )