Well, its interesting to hear folks talking about the Danvise in such glowing terms. Then again, its not "pretty" like a Renzetti.
I just this week switched from my 9 year old Danvise. It is actually a Danica Rotary from Europe. This was purchased before Orvis started marketing them. I think, in its price range, it is the best vise on the market today. Strong (well, bullet proof would be more appropriate) and able to hold multiple hook sizes in a single jaw (Look! Up in the sky!)
I used the Dan-vise to hone my tying skills. I then learned what the 360 rotation can do for you. I finally needed to go past what the Danvise, a Renzetti or almost any other rotary vise could do. I bought the Nor-vise.
I look at the Nor-vise's ability to rotate rapidly as an evolutionary step in fly tying. These steps are as follows:
Hold hook in fingers
Hold hook with locking type hand vise
Hold hook with bench-mounted vise
Rotary vise (aka Renzetti/Danvise)
Fast Rotary (Norvise)
I think my appreciation comes from spinning wool. I've done it by hand with a basic turkish spindle, with a spinning wheel, and with an electric wheel. The Nor-vise is like the spinning wheel. Don't think I'll be giving it up any time soon.
Frank Reid