I first heard about them in the mid 90s, my highschool years, as part of the big mag vs cocker wars. At the time, I could only afford playing pump with my PMI Trracer and PGP and dream of those fancy semi-autos. Both of the big name high ends were out of my league in those days.
When I finally could afford something fancy in 2003, I went with autococker because my local proshop stocked them and had plenty of parts. I was misinformed by the shop that mags were gone the way of the dodo.
Fast forward a few more years and I had the opportunity to shoot a Spec Ops Tac-One Longbow at a game. I liked how the marker felt (though wasn't a big fan of the stock) and soon had my own AGD Tac-One.
Part of me wishes that I had known about the mags still being around back in 03. Now our family has 4 mags of various flavors to play with and we're happy.