Based on data provided here, it seems that the efficiency of the Sacrifice ability is, at best, 60% for engineers and 90% for SACU's. It appears to often be substantially less efficient than that as well...
I believe that the Sacrifice ability is not used much compared to abilities like stealth, jamming, etc. It seems to be too underpowered and too inefficient in too many cases. I propose that its efficiency is improved.
An example way to improve its efficiency would be to give a flat 90% efficiency for all units that have the Sacrifice ability (mass and energy costs could be fairly formulaicly equated for balancing this).
Alternatively, the current calculation system could be used, but with the change of peak Sacrifice ability efficiency of all units with the Sacrifice ability being improved to like 90% or maybe 95% (since it's often actually a lot less efficient).
(The above changes are just potential examples of ways to make the Sacrifice ability more efficient. If you have good alternate idea(s) for how the Sacrifice ability should be made more efficient, feel free to suggest them in this thread as well.)