SamF: Thanks for the info guys, I feel more educated already :)
That said, my soon-to-be ISP seems to think that this will not be an issue (I re-confirmed with a second person there today). Also, they have said that in their experience master filters / splitters tend to cause more problems than they fix...
WOW, they really said that ? and someone confirmed it! I suggest you take the advise of people like sbiddle. I can not believe that anyone would say such a thing, its so wrong its ridiculous.