I've also welded in many floor pans.. Here's a reason I wouldn't want to rely on glued in panels, if you're involved in a collision in a unibody car do you really think a glued in panel at your feet and legs will stay in place? I sure wouldn't want a floor panel pop loose during a collision, it would be like a giant razor blade buzzing around at your feet and legs cutting everything it touches. Being in a car crash is bad enough, now you multiply the danger with sharp edged steel cutting your feet off, not for me. Weld those floors in place.
Do you really think the OEMs who design, test, and build the cars would specify bonding instead of welding if the floor would "pop loose" in a collision? If the guys who design, test, and build the cars say bond the panel instead of welding it, you bond it. It's that simple. Also, bonding is actually stronger than welding, depending upon the application.
