Really you can do 2.5gbps for £50 with just two of them USB3.0 adapters. Don't really need the switch.
Use the USB <> USB on your main computer and NAS for the quick transfers, assign one IP address on the NAS, set up a share on the main PC direct to it.
Then for other devices just use the Gigabit port on the NAS into your router on a different IP.
I use RAID10 on my NAS for quicker reads and writes. I believe it is the recommended RAID for 4 drives. I have just Western Digital blues and it maxes out the 2.5 Gbps fine. More than 2.5Gbps you would need SSDs so it is perfect for my set up.
When set up like this without the swtich, I also had to make my computers motherboard 1Gbps network adapter the priority metric. As before websites would hang trying to reach them through the USB 2.5gbps adapter.
1Gbps main network adapter - metric 50
2.5 Gbps adapter - metric 100.
Lower metric the greater the priority. So Internet requests work as normal.
This the driver for my Synology NAS which works perfect with that adapter pictured.
Synology DSM driver for Realtek RTL8152/RTL8153/RTL8156 based adapters - bb-qq/r8152
github.com