I did it 2013/03/12 just before Eric's Fagnan Multiplayer Balance Changes, so my Geth Spitfire had 70.6 damage per round (now it has 77.6). Also Prime's Siege Pulses flew through my Hex Shields - BioWare fixed this bug. With this changes, if I would play less carefully, i think it's possible to achieve less than 1 hour time (my first attempt finished in about 70 minutes, but I played more risky and died without any single Medi-Gel or Ops Survival Pack 8 seconds before extraction :/).