I have the remote and find it's not really that usable. It certainly doesn't work inside apps, which is where I would use it the most if it did work.
The 304T doesn't have the IR receiver built in, so you need the kit with the USB receiver to use it there.
The 6210T should have the IR receiver built in and the remote should work without the kit on this device.
I'm seriously thinking about getting one of those small wireless keyboards/track pad units to use for running on the NAS, so I don't have to have another set of keyboards/mice setting someplace close to the machine, as well as the 3 I already have for the desktops and laptops I already have on my desk...
Something like this: http://www.banggood.com/2_4G-Mini-Wirel ... 79475.html