One of my big concerns for this tier of progression actually centers on the roll. Snipers and gunslingers get very limited defensive cooldowns, namely dodge (only works on limited attacks), a personal shield which absorbs a moderate amount of damage, and the long-cooldown raid-wide 30% DR shield (our primary raid utility which many groups save for scripted times, and is generally unavailable to use as a personal cooldown). With large spikes of damage becoming more common in NiM raids, especially TFB Kephess' jump, and to a lesser extent the grenades on titan 6, I sometimes get killed from full HP through the one reliable short-cooldown defensive CD I have, and have to figure out ways to avoid the damage using covered escape or a sage MUST bubble me to avoid me dying. If avoiding damage from a mechanic by rolling isn't intended and is due to be fixed, snipers and gunslingers will sometimes just get oneshot on fights without external cooldowns (i.e. a sage/sorc shield or a guardian/jugg tank AoE taunt). If it is intended, it should be a little more forgiving on the timing required, as the current dodge-roll has a very short window where it will successfully negate damage.
My question is, is this a bug that will be fixed (will gunslingers and snipers be reliant on having other classes in the raid to live through certain mechanics)? Or is it intended that such a difficult to use mechanic as rolling exactly 0.5-0.7 seconds before getting hit is a defensive cooldown we should master, making it the hardest defensive cooldown to use in the game?
I can't say for 16-m but in 8-man NiM TFB (havent done SnV yet), i did not find a mechanic that insta gibs me from 100%hp to 0% hp. I dodge Kephess' jump yes but the last time i failed to do it i had around 25% hp left (i think i was sorc bubbled as well).
I learned from DiLiH that you can roll ~exactly 1 second before whatever is going to hit you is going to hit you and that will make you immune to the damage. For NiM DG Lightning surge if you roll with 1 second left on the cast ~more often than not you will get no damage from it at all. Kind of a hit or miss and can be duplicated with more runs and practice. I like it and its kind of fun >_<