Given that the op has a similar room to mine and I can’t really listen beyond -10 I can’t imagine it being tortured to the point where port noise is audible in normal usage.If you listen loud then possible port noise would be annoying. There is comparison between these two at AVSForum (US) somewhere, the Monoprice didn`t make noise where as SVS did when "torture tested". Also many reporting the Monoliths sound unique, different than most brands which is one reason why they so popular.
SVS does have better support/service. Number one reason why people swap the PB1000 seems to be most cases the lack of mid-bass if you look around real world reports. So i think both models are quite similar in that way, however they really excell with the deep stuff.
I’ve listened to war of the worlds on blu ray at -10 which was absolutely insane volume levels and there was no audible port noise.
That film goes real low with loads of bass as well.
In a bigger room it may be more obvious though.