I think this is really some fantastic modeling work, and it's gonna look great. Gameplay-wise though, I just really feel that the SH4 engine is going to make this a rather strange and awkward experience, especially when you consider that for instance even the Type XXI/XXIII in OM can't work correctly due to the snorkel ventilation and high battery capacity simply not working.
Seeing a nuclear sub getting bombed by Migs, while a great visual, I can't help but think something like this...
...as an approximation of the SHIV engine representing cold-war era combat. It's really too bad SH4's engine has nothing to account for the sonar operations and modern ASW (including sub-to-sub combat) of the era. Cause it's certainly got a lot going for it with graphics, crew management, dynamic campaign, etc.