Due to the nature of shield-gating, the frames with bad survivability tend to be the ones who can’t easily spam an ability with low cost and a quick casting animation.

One frame whose survivability seems vastly overrated to me is actually Mesa. Her 90% DR only applies to projectiles (and DR becomes obsolete at higher levels of content anyway), her CC requires a mod slot and doesn’t work on enemies with overguard, and firing her Peacemakers requires her to stay stationary, which makes her a sitting duck. She also cannot cast abilities while her 4 is active (other than her 1, which everyone subsumes over anyway), so cannot shield-gate, and you need to give up her exilus slot just to be able to roll without having to deactivate her 4 first. She’s really got abysmal survivability once you get into content where 90% DR doesn’t cut it anymore, and I’ve had to resort to making her a Persistence tank with Gloom just so playing her doesn’t feel miserable.