Voted 7 IDP, but we use 8 in my league.
2-3 DL, 2-3 LB, 2-3 DB. Which essentially is 2/2/2 with 2 flex that have to be in different spots.
Most of the time it becomes 2dl/3lb/3dbs, but with 40 man rosters most of them are offense, injuries/byes sometimes require a 3rd dline.
I'd like to make it 3/3/3 but for some reason being forced to start a 3rd dline is scary for the other owners, as most only carry 3 anyhow.
After doing IDP for the last 2 years, I greatly prefer that to team defense.
I don't find myself spending too much extra time due to the IDP, but I suppose it is a tad more, maybe 30-45 minutes a week. Generally just reading anything Bramel writes. If you're in an IDP league and arn't familiar with Bramel's work then I feel very sorry for you.