Speed

Room interaction can depend on whether or not there are ports and where they are.  Port location can definitely make a difference in how a speaker interacts with the room.  This can give better bass support but can also excite room resonances more than a sealed box or one with a passive radiator. 

Room interaction in the bass is, in my experience, more even when the speaker has a down-firing port or ports firing both forward and backward.  Passive radiators don't seem to have as much tendency to excite the room as ports do but I'm not sure if that's really true.  The tradeoff is that the bass is less well-defined with multiple or down-firing ports.  It's not troubling but it's also not great.  The best bass is from sealed boxes when your system is in a large room in a house that has fairly lightweight construction.  That way a lot of the bass will escape through the walls and you won't get the huge variations due to resonances.  

In my opinion it's also important to have a small midrange driver.  It makes  the dispersion more even so the off-axis response in the upper midrange isn't beaming as much as it is with a large midrange.  That makes speakers much less sensitive to the room.  The room can still be too reflective but the reflections will sound pretty much like the direct on-axis sound so the overall balance doesn't get thrown all out of whack like it does when speakers have a large midrange.