I currently have a "Gaming" laptop with an intel killer ac 1550 which supports doubleshot pro (combining the wireless and wired/ethernet connections as one connection however I can see the benefit of that also in my planned custom build? Are there network cards that need to be bought for it or is it more limited and less available to desktops?
It is pretty much silly concept that nobody actually needs. Even though intel now own killer you need to run as fast as possible away from anything killer.
So question 1. What traffic are you running that you have exceeded the bandwidth of a 1gbits interface.
Question 2. If you actually are using more what are you using for disk subsystems so you do bottleneck on the disk systems.
You NEVER want to use wifi for gaming when you have a ethernet port. Wifi is always subject to interference from neighbors wifi usage which will cause lag in games.
Now sure what application you would have that needs that much bandwidth but in a desktop system you just put in faster ethernet ports. Many come with 2.5g and even 10g are not expensive. What is expensive is going to be what is connected on the far end like a NAS or something that can really run at those rates. Internet connection are very rare that run above 1gbit and most times it doesn't matter because the servers you are getting the data from have artificial limits to prevent people with fast connection from monopolizing the connection.