I went through the same decision a couple of years ago. I was comparing both the Renzetti Presentation 4000 cam and the Dyna King Barracuda vise.
A buddy of mine has the Barracuda vise, which I tried out. The stainless steel components make this vise tough, I doubt you could ever wear out any parts on it. My main beef about the Barracuda vise were the jaws. I found the groove for the larger hooks to be annoying, a lot of the time the hook just didn't fit properly in the groove. It was a bit of a shock whenever your tying a big saltwater or steelhead fly and the hook shifts out of the groove in the jaws. The Barracuda is also a bit bulky or large, which makes it a bit difficult for traveling.
Another friend of mine has the Renzetti Presentation 4000 vise. He has tied thousands of flies with his, almost all chironomids though. I tried it out, just tying chironomids. I love the vise, very smooth and easy to use. I found the smooth jaws held hooks very well. This vise is lighter and easier to travel with.
The only thing I didn't like about both of these vises were the fixed angled arms for the rotary head. This means your hook has to be positioned so that the shank is inline with the shaft of the rotary vise, so that when you rotate the hook it spins on it's own axis.
I kepted looking and found the Renzetti Presentation cam 2000 vise, which has an adjustable arm much like the top of the line Renzetti Master vise. Sure it is not quite as flashy as the 4000 with the gold anodized parts, but I didn't mind the matted aluminum finish. The Presentation cam 2000 is also cheaper than both the Presentation 4000 and Dyna King Barracuda vise. I purchased the Presentation cam 2000 vise and am very happy with it. I have tied everything from #20 chironomids to giant 6" long intruders on it
The bobbin cradle is very handy for hanging blank shank/stinger and big articulated flies. My only wish is that it came standard with a material spring clip.