I never play the same list more then once so I have benched everything just because. 
Discussion Time: Benching a List
I had my 3 nebulon jousting list back in wave 1 that got benched due to being unable to compete with Assault Frigates swirling (and demolisher flanking). I'm toying with updating with some tricks and trying again nowdays. That's probably the only list I've put aside after having fun playing it. I do always keep trying new lists though, just to try different builds, combos, and playstyles. I may only play that fleet 1-2 times, but it's not "benched" (meaning avoiding playing it), I'd play it again if I wanted to. Now that I think it about it though, I have benched my DeMSU. It was fun to play, but after taking it to two tournaments, I'm ready to play with other stuff. It's a competitive list, but has its weaknesses.
What do you think are the demsu's weaknesses?
Being outbid and Rhymerballs. Both make for a very tough matchup. Definitely not unwinnable by any stretch, but it's a tough game. I've gotten tired of the bidding war, and also Rhymerballs are so common I'm not using a DeMSU for a while.
I had my 3 nebulon jousting list back in wave 1 that got benched due to being unable to compete with Assault Frigates swirling (and demolisher flanking). I'm toying with updating with some tricks and trying again nowdays. That's probably the only list I've put aside after having fun playing it. I do always keep trying new lists though, just to try different builds, combos, and playstyles. I may only play that fleet 1-2 times, but it's not "benched" (meaning avoiding playing it), I'd play it again if I wanted to. Now that I think it about it though, I have benched my DeMSU. It was fun to play, but after taking it to two tournaments, I'm ready to play with other stuff. It's a competitive list, but has its weaknesses.
What do you think are the demsu's weaknesses?
Deployment, deployment, deployment. By their very nature, they are activation heavy and deployment light, so if you can delay your biggest prizes from popping up on the table until the key piece (Demo) is down, you can make it run a gauntlet. One of the reasons I always build my lists with 7+ deployments at a minimum.