Some of the pills you will loot from the strongboxes can be sold ingame, and have decent MU. I doubt you'll need them, and you will get untradable ones for sure which you will have to eat anyway.
So, with a 90 % efficiency gun and 80+ looter level you can expect tt returns of 98 % in the long run (given enough kills), which would mean profit to most people.
With a typical armatrix efficiency of 67 %, and level 40 looter, return would be in the 93.5 % area = eternal loss for most people, unless very lucky.