I think the OB 5's could handle a little more due to the fact they are a 3 way speaker. An MTM section for high's and mid's and a ported WW section for lows. The AV/3's are a 2 way MTM in a transmission line. The OB 5 uses the same M-130 mid-bass driver, but has more of them, so of course less distortion and more power handling.
Danny's better able to answer your questions though, about whether to run them front ported or sealed, and how that would affect their performance.
Cheers