I only carry the one phone. Even if I carried two (one for tethering, and one for communicating), it wouldn't change that part of the problem -- no matter which device is the voice/txt device, given my job, I have to answer it ... or at least check it to be sure it's not likely to be an important call/message. Which means juggling the tablet and phone every time I get a message/call, unless they're the same device. That got old REALLY quick.

And that doesn't mean I dismiss the multi-device camp. The Unix way is specialized systems that interconnect to leverage each other's specializations. I love and respect that. But, in order for it to work for me, only one of those devices can be my "user interface" (email, rss, web, ssh, vnc, phone, sms, im, etc.). Having a mifi/cradlepoint device* that was also an SMS gateway and SIP server with decent battery life, and having a tablet that supports that mode of operation, would in fact be very compelling to me (assuming strong enough security between the devices). Other compelling pieces of such an environment would be a pocket-wireless-NAS (BT hard drives, for example ... which have yet to be released in the US, as far as I can tell), a Tekkeon type battery for keeping the devices charged, and a camera that can utilize/inter-operate all of those. However, several pieces of that puzzle are missing. Especially the security component.

(* it could even itself be a phone ... but the most I've seen in a phone, for fulfilling this role, is various low-security wifi data router options ... no voice/sms service routing)