My understanding is that you need to add TMO 2.5 to SH4 v1.5. That is the edition that contains the U-Boat missions and some fixes not covered by the v1.4 patch. You can get the v1.5 version from Subsim.com for $9.95 at last look, although I did not verify that today. Personally I like TMO, but have mixed feelings about TMO+RSRD. I think I like the higher degree of randomness that TMO alone offers. The RSRD is pretty much predictable, in that if you encounter a certain juicy target, such as two IJN carriers rushing to the Coral Sea in one career, in a subsequent career you will most likely find them in the same place at the same time. That repetitiveness gets to be a little off-putting, especially after multiple careers over a number of years. But, to each his own.
I do recommend the v1.5 update, whether you intend to play the U-Boat missions or not. Good Hunting!
