The tonnage requirements vary between certain amounts. Sometimes it could only be 2,000, other times 10,000. The role they play is to keep you from simply going to each patrol point, hanging out for the 48/72/96 hours, moving on, RTBing without firing a shot and getting a promotion. You do gain renown for simply reaching patrol grids and staying there for the required time. You just won't ever gain enough to earn promotions very quickly, if ever. The tonnage "requirements" are different at each objective and I think according to the readme file are random.
Promotion requirements are given to you by clicking the "promotions" book on the desk in the office. It lists each rank available and will state "You must complete at least 3 (or more depending on rank) at a level of "Good/Excellent/Outstanding" to reach this rank".
The only thing I dislike about "OM" isn't actually the fault of the mod itself, but rather the SHIV game engine, is the fact that the boat doesn't ventilate while snorkeling. CO2 continues to rise and you still have to surface from time to time to reset the CO2 counter. It's a petty annoyance, but I have been killed once or twice as a result. Surfacing to get "fresh air" real quick and "RADAR SIGNALS DETECTED", then as I'm crash diving catching some bombs or depth charges.
Bugs not caused by the mod itself aside...
The late war is a real bitch, as it should be. Aircraft are pretty savvy at picking up your snorkel on radar so snorkeling has it's hazards. It's not like SH3 where you can snorkel around and be pretty much safe from air attack. (Never once got attacked by air while snorkeling in SH3/GWX)
The escorts are good, and there are escort difficulty options that you can activate with JGSME if you wish to have a greater challenge.
Resupply from Milk Cows is done well too. Instead of them being "static" entities that hang out in the same spot for months at a time, they move around and are only available in each location for a short period of time. Radio messages from BDU are sent out letting you know when and where they'll be available. It makes doing long range missions a little more challenging because you aren't guaranteed to have a supply boat available when you may need it.
@Platapus,
OM is comparable to GWX in it's scope of operations, so if you don't ever want to go near Asian waters in a U-boat, you don't have to. The Atlantic Theater is your playground
