Got both sets at Mk XI (lots of grinding and luck) and being honest I prefer the MACO set, while the Tetryon Glider is nice and you can make the gates in the STFs spin like a top with Gravitic Anchor the MACO set does more to help survivability (at least for how I play).
For a decent tanking effect, I've found that the Borg engine, deflector, and module, combined with the MACO shield does very well on my escort. 3/4 pieces are needed for the shield and hull heals. Both have saved my skin on more than one occasion. You'll lose the tractor beam by breaking the set, but if you want survivability, I've had very positive results with it.
The graviton beam with the MACO set is pretty darn useful at smacking spheres away from transformers in "Infected," but that's about all its good for.
Hereout I'm referring to the MkX version of this set that I've been lucky enough to pick up through drops. I am still working towards the required numbers of EDCs to pick up the MkXI, but will be doing so at the earliest opportunity. It really is that much of a no-brainer for me.
The benefits of the MACO shield, in my experience with it so far (Sovereign/Fleet Escort Tactical officer) are ahead of the benefits you get from the Aegis and Borg shield.
While it is true that you've got slightly less capacity than the Covariant Aegis, you've got several considerable advantages. Firstly, your shields resist 10% of all energy damage and plasma damage by 20%without even proccing.
Second, your regeneration rates are higher than the Covariant,
Third, with all its capacity, resistances and bonuses, it's a resilient shield. This means you're taking only 5% damage through the shields, compared to the 10% you get from the Aegis.
Where the engines are concerned, you're getting +20 to your turn rate (Compare to the Aegis and Borg at +6.4) and the ability to pretty much ignore Tractor beams (Well, not quite. You get 25% thrust even when held) and, assuming you care about sector space speed, you're getting +7 or 8 to your Driver Coil.