Engis should go full INT and max Empathy, Revive, Transference, Pain and Sonic Boom (in my opinion). Maybe even Decay, if possible. Transference is a vital skill for engis because of the AoE and healing properties. Sonic Boom is the only other AoE skill, and admit it, they really help while tanking.

Runs with more than two engis are slow because of the DoT. Ops have high DPS and comms just need to tank and take down enemies. Engis may have high weapon dps (though not as high as ops) but their skill DoT makes runs slow.

I hope I helped.