I really wish their LightSpeed devices also supported bluetooth. If I take my mouse with me on the road it's really annoying having to bring a dongle and the adapter.
I use a G603 LightSpeed which also supports operation via Bluetooth. It actually ends up being pretty handy, as I can switch the mouse between my desktop and laptop just by pressing a button.
Beware though, that they have an issue with scroll wheels breaking after several months of use (a plastic axle connecting the wheel to the rotary encoder breaks off). After mine broke the second time after warranty repair, ended up ordering a replacement part myself and also modded the scrolling mechanism to have less resistance.