I ran 250 rounds through my 930 in about an hour last time out with the side-saddle attached and no issues with separation whatsoever.
I can tell you the receiver got pretty hot too. Make sure you use the industrial strength Velcro and you shouldn't have any problems. I know
@oli700 isn't a fan of the concept due to having experience with Velcro adhesive melting after some time sitting in a hot truck. My shotguns only stay in my truck long enough to make it back and forth to the range, but they do sit out on uncovered tables in direct sun during regular trips as well as matches where I might not shoot or even handle them for 30 minutes or more between relays. Not exactly hard use, but I'd consider it pretty regular use and I haven't had any issues yet...