I get calls asking which is better and why we have two attachment methods. As for which is better, the only one that clearly work better is the 3M in extreme cold. At 30 below we couldn't pry the 3M tape off a hard top where as the adhesive on the Velcro became brittle. That being said, we have not had a single complaint of the Velcro coming loose in the cold. Both the 3M and Velcro work excellent in extreme heat, and if your hard top is cleaned well with acetone your headliners will stay in place until you want to take them down. 
We have had a few issues with the 3M tape not holding. I'm confident that we have solved that issue. The problem was that to get the 3M to really stick to the hard top required a lot of force being applied to the headliner panel during installation. That took a good amount of should strength that not all our customer possessed. We have a new installment process that does not require much force. Basically, the 3M tape is applied the hard top first, and then a roller is used to make sure the tape is firmly stuck to the hard top. Then the headliner panel is slid in place and pushed up against the waiting 3M tape. The tape sticks to the headliner panel material much easier that the hard top, so it doesn't require much force to stick properly.
CLICK HERE to watch the new 3M installation videos.
We are also making one more change in the installation process, instead of using alcohol to clean your hard top we are now calling for Acetone to be used. We have found through experience that it works much better.