I usually set it at 1, but there are certain situations where I go higher. If I'm in a progressive league, and facing a team with 1-2 stud hitters and not much else, I'll jack it up a bit to try and pitch around those stud hitters as much as possible.
I like the idea of an IBB setting, but I would like more control over it. Obviously it would be more complex, but I'd like a setting that somehow allows you to target specific hitters you want to walk, rather than situations. It's like the team SB setting in HBD...if I have 3 really good basestealers on my team, and 6 guys with cement feet, I can't really apply a setting I like to my entire team.
I never played live much, but I would imagine being able to strategically pick where you use IBBs would come in handy.