You need to run two copies of EPtS for a constant resistance buff. It's more or less a requirement.
I also highly recommend using a key bind that will distribute your shields for you. I have mine set to space bar, so I'm constantly distributing shields while firing weapons.
Devs would like a concise list of things that are broken and not working currently, so here's a short list for PvP: Neutronic Torpedoes, Ionic Turbulence, Surgical Strikes (including Faeht firing through cloak), PartGen stacking and CrtH being boosted to absurd levels.