I had the option of buying my N-2 with integrated comms, but didn't because that doesn't have a phono / straight- out option.
I like plugging in my WIRED Etymotics earbuds, as I've said before, in-helmet speakers are no protection against wind noise and hearing loss.
So, if you use earplugs AND helmet speakers, there are two devices at cross purpose to one another.
The Sena 50S has the boom mic and a phono-out plug, and I can recharge it on the bike without having to remove anything.
I've only needed to charge it on my return trip from RawHyde / Kalifornia bringing home the GSA, but I just ran the cable from the USB charger on the bike straight to the helmet, and it charged pretty quickly.
But I suppose future models will do away with that feature (speaker / audio out), just as most modern phones no longer include a headphone jack.
As I don't do calls on the bike, I've not yet used the microphone except to return a missed call once I stop, and it IS convenient not having to remove the helmet for making a call.
Haven't even looked at the N-3 yet.