Not nearly as popular as Marcus because Marcus is a much bigger name, but it would definitely give R Cocco a bump. But while I'm sure a lot of folks will try them just because Marcus is using them, nobody's going to stick with them on the sole basis that Marcus uses them. You still have to like it to keep using it, otherwise you should be checked into a mental ward. But that's how it works. Endorsements sell. That's why companies fall all over themselves to land guys like Marcus or Richard Bona, or me
Me, I'm not going to try them. Not available in my wuss gauges. I don't sneer at higher tension but I gotta have my wuss gauges. Plus I'm quite happy with dead Super Bright Nickels for now. I've always wanted a real versatile string that can do a credible dead flatwound tone and a credible new roundwound tone (I know, right?), but if you let Super Bright Nickels go dead, it's about as close as I think you'll ever get to attaining that goal. Mine aren't super dead but they're dead, and I usually hate using dead rounds but this is working for me.