Finally figured this out... it was buying an Android that presented the solution...
Well, I bought an Android last month, a Samsung Galaxy Note 2, and in the process of finding a good sync solution with all my Macs, I discovered that Syncmate from Eltima has a SMS reader / sender built into the software. So now I can just fire that up and click SMS manager / new SMS, and type in a SMS on any desktop or laptop and send from there, via my phone's connection. Not tested, but this should also work with an iPhone connected to Syncmate. One bug noted: I can only send to one contact number at a time; if I load up a list of contacts, the message is only sent to the first one in the list. Have not tested groups... but perhaps that's the work around. Syncmate can be had for 30 bucks, and IS THE BEST solution for syncing a droid with a mac, to include contacts, calendars, folders, iTunes playlists... expensive, buggy, but after weeks of research, the only thing I found that comes close to a solution.