Well, I just did it. I had to download a new version of their Bluetooth Device Manager (v1.4 for Mac), but after that it went about as easily as the previous upgrade.
As before, the process isn't particularly intuitive. There are the same Bluetooth warnings as before, but at least it didn't deactivate my Mac's Bluetooth system this time (it did the first time). The onscreen instructions are pretty straightforward; plug in, switch on, and go thru the steps. You'll get to a point where it asks for the upgrade file - click "Download" and you'll get the 4.1 file. I almost clicked past this screen before I noticed the "Update" button. As before, you need to babysit the process and hit certain buttons when asked. Once the update is finished, you can click thru to the "Device Setting" screen (I think that's what it was called) where you can select various options (a couple of new ones in there).
Quit the program, unplugged, snapped it back onto the helmet and re-started the SMH10. As with the last firmware update, you have to re-do all your pairings and volume settings. I cleared the old pairings from my iPhone 4S and zümo 660, then followed the instructions for pairing the phone first, then "multipoint" paired the zümo.
It all worked! I had to re-set the volume level (on the Sena) for each of the devices (with earplugs in) but after that, it remembers them. It did start all the way turned down, so don't panic if you don't hear anything at first. Just turn it up. And Siri seems to work about as well as before.
One difference from before: When I switch on the SMH10 with my phone in my pocket, I now hear two beeps and "phone connected," and that's all. It used to add "device connected." Works the same in any case - music and telephony from the iPhone, directions from the GPS. Haven't really played with it too much yet, but so far, so good.