Back when I was on Helio, I had two phones and it was trivial to go to the web and swap out which was active - because sometimes a simple, small, tough, flip-phone is really all you need to carry. I understand that is similarly easy to do with a number of carriers, so anyone interested in the two phone strategy should check that out, as I guess it varies by carrier.
I didn't know that the BT800 was so finicky, no wonder they discontinued them.
I now go with a wired headset, I like the sound quality. I guess that makes me look like I'm wearing an old hearing aid or transistor radio. I don't worry about it any more than I did borging up with Bluetooth - probably I'm so drop dead handsome that people are going to stare and smile no matter how I roll. Speaking of, rotf!
In any case, I still think that the overall idea works for a multi function BT with a tablet, but I guess I don't know what the right one would be.