I think most everyone has summed up my feelings on this topic but for what it's worth:
- I've gone with all manual. It's not perfect but it's much more enjoyable that anything semi-assisted for me.
- Even though manual shooting is tough and I've missed some goals that have costs me some games I still prefer it. If I play on semi-assisted then I feel like I can win just about any game I play and I feel like my shots are very scripted. On manual I feel like if I make a goal it's b/c of something I did - as opposed to just jamming the controller to one corner and hoping the keeper doesn't make a miraculous save.
- Online Head-to-Head - I'm getting beat regularly b/c I'm playing ping-pong passing players on semi or full-assisted. But I don't care - it's still much more enjoyable to me. I don't really care about my ranking or win/loss record - I just want realistic matches. I agree that when I'm using manual and they aren't that I get pressured way to quickly and they usually dominate me. This gets frustrating. But every now and then I get some really good games.
- Online Team Play - I really enjoy all manual here. I've been able to open up some really good plays when playing in the midfield. I'd bet that 98% of my team mates have no clue I'm on all manual until I whiff a goal that I should've at least hit on target. But again, I don't really care what they think, it's more enjoyable for me this way. And for what it's worth my player rating is usually in the top 3 every single game and for some odd reason this keeps me interested. If I could find a group of regulars to play on a team with that used all manual I think it would be awesome!
- Manage mode - I've started with Middlesborough in the Coca Cola league and using all manual here can be quite the challenge. I feel that the play in MM is different than just random exhibition matches and it probably has a lot to do with momentum from game to game. But I'm having trouble getting time to get off quality shots so I'm loosing more games than I'd like. But having said that, I am playing with a lower level team that shouldn't be winning all of its games so it seems to be realistic.
In summary, for me, all manual is the only way to go. It's not perfect but it's more rewarding for me.