That would make sorc bubbles last longer, which would increase sorc power relative to other healers. If anything, people have been crying nerf on sorc bubbles. If Static Barrier absorbed something like 98% of each hit rather than 100%, the target's defenses could still be processed. You always have to think of the unintended consequences with these things, though.

In other words, ion cylinder makes or breaks a tanking role.

I'm still leveling my powertech (22) so my input is not expert, but here are a couple simple tips: If I remember correctly, the tooltip on Rail Shot says something about the target needing to be incapacitated, but Rail Shot will activate if the target is under the effects of a damage over time ability. Other than the DoT from combustible cylinder, you have to go looking into the skill trees to find one. Shield Tree - Ion Overload should be the next talent you take. That will make Rocket Punch -> Rail Shot a predictable high damage combo for you.