I never really thought of wireless USB devices as being that great. The USB receiver takes up a port constantly whereas Bluetooth leaves your computer free to connect to other things.
However, while exploring Surface + mechanical KB as an alternative to a clamshell laptop, I realized that USB receiver based wireless devices work as USB devices on the machine. This is important because they don't need to be paired or have any other ceremony performed before they're operational. Which is a big deal when your OS requires a password before it can boot.
I've been using a Matias Secure Pro and I'm missing my more compact and custom layouts. Does anyone here know of wireless USB systems for DIYers?