I've been messing around lately.
Here is something i have testing:
I like using ION Cell for the extra armor and such.
I find this spec works very well for guarding healers while still being able to dish out some DPS.
I did a round last night and received my first ever, 20 medal game. Do not recall the exact numbers for damage and protection, but I had a great healer who I guarded. Basically, we could not be killed.
Im sure it has some fine tuning, but I liked what I saw last night.