We currently have Sage. We just switched to them a couple of weeks ago. I am happy with the phone service, but the savings was not as great as I had expected. There is a line charge that is included in your SBC price, that is not included in the Sage price. Therefore, my great savings went out the window. Overall when I compared both bills we are saving about $3 a month. Not much, but at least something.
SBC always invents new specials to lure customers back, so maybe if they have something good we will return.
But again, I haven't noticed any difference in the quality of our phone service.
Hope this helps.