Considering a Clay Change

My normal throwing clay for home is Standard Clay's 105 or 105G (with grog). Also I work with a red clay in the same series, 104. Recently my mother (who does a lot of glazing for me) asked if she could use mid-range stoneware glazes. This brought about a question in myself... can she? I know my 105 earthenware would never survive to those temperatures, but on the other hand, if I were to change clays, then it would be possible to fire higher without risk. In some ways, 105 is not a very versatile clay, but its easy to work with. I had previously used Standard's 551, VP Porcelain as my mid-range white clay. I had a love-hate relationship with it. It would throw thin, light and stretch easily, but it wasn't durable at all... many pieces in it broke before they were even fired. I was running low on clay the other day so I have obtained 100 pounds of a clay I have never worked with before... Standard's 563, a white mid-range stoneware that is completely vitreous at cone 6. I'm looking forward to trying it next week. The description I have read for it sounds a lot like 105, so I might be very happy with it, but no way to tell until its on the wheel.