For Mac users, I just braved the beta firmware update (4.2 for the SMH-10) using my iMac i3 for the first time (OS 10.8.2).
Despite the "sky is falling" warning from the Sena device manger app, I did NOT have to find a wired keyboard or mouse or disconnect any BT devices, including mouse and keyboard, and the update went smoothly.
Weather is too crappy for a road test of 4.2, but after performing a factory reset and re-doing all the pairing, it all works fine on the bench [g].
2009 BMW F800 ST
Never let your motorcycle take you where your brain hasn't been five seconds earlier.