So nobody answered my question in the internet speeds thread. I was going to post here, but I figured I could try to figure it out myself instead of being completely lazy. I knew I needed the wifi QoS on with my 200/5 comcast service because the 5 is so low that other devices could get completely boxed out if someone is using an even nominal amount of upload.
Netgear Support wrote:Note: If you use a gigabit Internet connection, or your Internet download and upload speed is 300 Mbps or faster, then you don’t need to use Dynamic QoS.
I figured I'd post anyway in case someone else had the same question. It is faster over ethernet with QoS turned off.
Even with high bandwidth, you still can have problem with bufferbloat if your household usage can max up the bandwidth. If you have that problem, you probably don't need QoS but you need SQM.