Hi, and welcome chaserbren!
DMB and OOTP are both great games, in my opinion, but for some of the reasons other people mentioned above, we'd love for you to give OOTP a try.
One thing I should point out about head-to-head: while there is no head-to-head mode today (or in the upcoming OOTP 10, sadly), there is a new option available in OOTP as of last year called "replay." Most OOTP leagues simulate games, and the output of a single game is typically a game log and a box score. However, with "replays," you can actually choose to save the complete play-by-play for each game. Of course, I'm not claiming that it's the same thing as making the in-game calls yourself as in a true head-to-head, but it does allow you a greater degree of insight into how the games actually went down.
Not sure if that's "good enough" for your constituents, but I thought I would mention it!
Of course, someone else mentioned the customization. This is particularly cool for online leagues, as the game generates a huge # of HTML reports that you can share with your leagues. Here's one of many examples:
American Baseball Association Home
Let us know if you have any other questions!
Thanks,
Steve