Is this a good setup? [Pro 6 + drives + switches]

I have had a GS108 on my network for over two years with a mixed speed devices for over two years with never a problem. However, the only FS devices I have are printers. All the desktop PC's (2) are gigabit and of course the ReadyNAS units (2) are as well. The printers are connected to the router, which was initially had only fast ethernet ports, but it was replaced by a newer router with 802.11n and gigabit ports as well. Of course the one laptop connects to the router and only interacts with the NAS units if I need to save or work on a file from them. It normally is used to browse the internet.