I've played with the Kruos and got the Med-bot augmentation.
My ship got destroyed before getting a med-bay. Now I wonder if both augmentations together can cancel the health loss that most races suffer in vacuum.
An entirely oxygenless ship would be a good defence against boarders. Having the advantages of non-lanius races in addition to that seems to be a desirable setup.
Best Answer
With a little math we can figure out the answer:
From here we know that with the medi-bot active, it takes 10 seconds to do 50% damage to a crew member, so the crew takes 5 HP/S.
Normally, it would take 15 seconds for a crew member to die. From that answer we also know that vacuum does 6.67 HP/s damage.
So medi-bot basically heals for 1.67 HP/S.
Emergency Respirators reduces vacuum damage to 50% (3.33 HP/S).
So no, the medi-bot alone won't be enough for your crew to survive in a vacuum. However, crystal crew members, who already take less damage from vacuums, will be able to survive indefinitely.