Dudes, it mostly boils down to three things: ship upgrades, loyalty, and picking the right people to do their respective jobs. It doesn't even matter when it comes to other equipment upgrades as each team member has their own innate "defense score" for the hold the line segment. I personally send Tali because of her low score and lack of versatile abilities for the final stretch and because I find Mordin's incinerate to be helpful in that final leg of the game (and because of his own low defense score) along with Kasumi to take out some of the weaker mooks (alternatively Miranda due to her class buff to the entire team). But even then, loyalty bolsters the overall defense score so that who you take to face the larvae doesn't really matter, as long as you send a low score teammate as an escort.
But if you don't have full loyalty, you are going to have to get creative
Where did you all get the impression that actual equipment somehow came into play?
EDIT:
Voltaire said
No way man, I've been upgrading everything and I did all the loyalty missions and I picked the right people for the different parts of the mission. They all survive just fine up until I leave to kill the reaper. Maybe it's because I play Renegade?
Weird. Just take Mordin with you then, he should survive if he has loyalty.
