BTW, the reason I didn't use snaps is that some of my original snaps were missing and my floor boards are a bit thin in certain areas from surface rust. I removed all the rust and treated the metal before installing the new carpets, but didn't want to screw anything into them as this could accelerate rusting.
The velcro was a perfect solution for that reason - and was suggested by Tush (M Pied Lourd)