I think Mag's big beef was the 2AA format and twist on/off design. I can't find it but there was a link on YouTube where they used an excavator to roll over all of the Mini Maglite clones that were seized after the lawsuit. They were all 2AA, aluminum body twist on/offs.There have been a lot of twist-on lights before and since. and Mag doesn't seem to have tried anything funny. And as Sween mentions the mechanism is different. Would be interested to know if the design of the lanyard ring was a trademarked feature. That's been present on several Mini-Mag knockoffs that got sued, but I don't recall the ring being part of the suit.
The Surefire is very very simple in design. I'm not a fan of how far the light has to be twisted off to turn off. It's really just 2 springs and when tight they make enough contact with the batteries to let current flow. I think these were discontinued by 1991 because they aren't in the 1992 Surefire catalog. There appears to be only 7,000 or so made based on the highest serials I've seen. There were 18,000 7D Maglites made over 3 years and I see those come up for sale way more often at prices way lower than the Surefire 6Cs.
I'd take a Surefire 6P over one of these any day of the week if I was actually using them in the field so it's not hard to see why so few were produced and why they weren't produced for long.