Here's some of my thoughts anyway for anyone who has the time
Of course getting survivors off as soon as you can is best if the conditions allow. Sure, I'm no expert and can't say whether it's unwise to surface the boat before removal of passengers, but to me it seems it might be easier - ok there would be issues of waves and movement, but at least you're on the surface (even if you're a few decks below). I guess survivors might get DCI before you could get to them though, if they were previously trapped in an airpocket, but chances are they'd get it anyway if they'd been down there for a few hours.
My thinking is - it's difficult to get someone out 'dry'. I.e. if they're in a sealed room (unlikely) - but outside is pressurised, cutting your way in forces water in and survivor has to deal with the subsequent pressure - if they don't know how they're screwed! If you enter through a dry room first, you basically then have a series of airlocks, the outer one of course perhaps being needed to be flooded and purged each time you go in and out.
If they're in a real airpocket, then divers can swim them out, but this is a more difficult if the pocket space is being slowly equalised from a small but high pressure leak. Two choices would be pressurise the room with more air, or flood it, but both methods would have to be done before you could reaching the survivor no?
On the surface you can go in from the top, and weld and seal as you go, then purge the section. Anyone you meet can exit 'easily'. Can this not be done? (n.b. Would need to balance the boat via the lift bags).
Things only take time because money is involved somewhere along the line, and things cost a lot because again someone is taking 'their cut'!!! Pirates, the lot of em! A rescue operation really needn't cost a lot or take time.
Still, I'd sure like to learn how real rescues are carried out when dealing with 'chambers' etc.