I was in the same boat about 2 weeks ago. Have been playing with auto targeting for all of SH3 and up until now in SH4. Mainly avoided it because I thought it would take too much time and make the game feel like more work than fun. After my 7th patrol the game just started to feel too easy so I finally decided to give it a shot. I just completed my 8th on manual and now I'll never do auto again. Much more satisfaction from manual. Would feel like cheating if I went back to auto.
I find that more than 90% of the time I'm using the Dick O'Kane attack method. Was a natural transition for me since I always tried to get a 90 degree angle even on auto. I surprised myself when I managed to sink 2 & damage one using this method for a convoy attack. Thanks to Rockin Robbins for the excellent tutorial I learned it from:
http://www.subsim.com/radioroom/show...6&postcount=67
A couple more patrols and I think I may be ready for Trigger Maru.