Just thought I'd tell some experiences.
The bad:
I had a save game CTD so I had to abandon the patrol where a hunter-killer group appeared. I was using the old version of Submarine Tracking Room, but I'm now off the mod, as I want to keep playing with my current setup to see if my game is stable or not. I nearly ever have CTD's, although I'm constantly tinkering with my mod soup.
The good:
Playing with the mod was absolutely great. At first everything went like in a usual SH3 game. Patrolling, then attacking a convoy. Managed to get a wolfpack attack, though. Then patrolling again, getting another convoy report - and then a warship group was reported heading straight towards me. I was suddenly attacked by an airplane. I ran away from the hunter-killer group at night time trying to get to the convoy. Then while getting ready to attack the convoy, I start to get radar warning after radar warning. In the hydrophone I suddenly hear - or imagine hearing - three groups of ships. One convoy with its escorts and two warship groups with fast screws. (I don't know if it's possible to have 2 HKG's at the same area, but I was on the border of two grids). I ran away from the site submerged all through the day, and maximum cruise speed by night
Then made a save 170 km from the last radar warning spot, and 120 km from my last radio report, the one save that didn't load.
I have NEVER felt that hunted in SH3
It felt real historically correct to me. There I was northwest of Madeira, two large convoys, and suddenly aircrafts and hunter-killer groups jump out of nowhere, and the the radio reports that the allied have made a landing in North Africa. And then I felt a great reluctance to keep attacking that convoy, just like many of the later war U-boat commanders must have felt as well.
It's the first time in SH3 I had to make a decision: "If I attack that convoy, I will get hunted by its escorts, and there is a slight risk of the hunter-killer group joining them, and a big risk of getting attacked from the air, if I survive and surface to air the boat and load the batteries."
Once I get my stability issues cleared, I'll install V2 and begin playing with that. And if nothing else helps, I'll not save at sea - I'll just hibernate the game and only save at ports.