You might be able to get full speed if it was 802.11n router but often our 802.11 router hit the limit at roughly 2.5, interference really ruins wifi connections and he's right ethernet cables have a much greater chance of getting the max possible speed on your connection.
You'll be limited to whatever your service maxes at regardless of how fast the ports are. That said, never hurts to have a fast local network and wired is super stable.
I only use a wireless connection when there's no other option. Like grabbing updates or syncing trophies for the Vita, and messing around with other wireless devices.
Most people don't realise how unreliable wireless is, I mean it may not necessarily drop out completely but the speed can vary.
If you're going to grab a cable might be an idea to go for cat6, that way if your net is upgraded down the track no need to worry about upgrading the cable too.
I doubt any US ISP is going to offer 10gbps service anytime soon.
looks like my laptop hdd finally died on me yesterday.
"I am... Sheik. One of the last of the Sheikah tribe..."