With gigabit or even 10Gbit internet, the QoS is much less of an issue than it was before when you used IP telephony with fairly limited bandwidth for remaining services. What you describe is extreme use case. I wouldn't even bother, just get the fastest connection you can afford and you should be fine. This is the direction where we're going, there will be more and more P2MP connections and running a third party hardware will be harder and harder (at least with traditional ISP providers).
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