I have William and Josephs Magnetic Chest Pack. The have 2 models.
Two things about it are better than I expected.
1. It is fast!. Opening and closing are instant. But firm. Also, no snagging tippet on the zipper.
2. The magnetic bead around the edge of the seal holds your bottom fly while you tie on the other.
I think people that reject new things based on long term habits are naive. You should try something new for quite a while to find the benefits over your habitual preference. You can miss a lot of good things clinging to the comfortable item from you past.