As regards cam vs. thumbscrew tensioning:
In the beginning, the Griffin Odyssey and Renzetti Traveler were both double thumbscrew. Both work so well I have never been persuaded of the value of "upgrading" to a cam version, and in fact, I harbor a fair amount of suspicion that doing so would lead to buyers remorse.
Now, the Griffin comes either double screw or screw/cam hybrid, whereas the Traveler comes only screw/cam hybrid. If insisting on cam operation, I would get the Traveler. I have seen some Griffins with cams that were quite clunky.
For just about any model vise you can think of, there are youtube videos reviewing them. These are usually not very exhausting, but sometimes you can note a fair amount of difficulty the user is having with the cam mechanism, even on some expensive models. This may or may not be a function of operator error depending on what you are looking at, but it does indicate that the presence of a cam does not mean there are no fine tunings needed.
I acknowledge that various cam vises have many adherents, especially from the likes of HMH, Dynaking and Peak, but I have no direct experience with them. These are all true cam vises, involving a collet mechanism. The Griffin and Renzetti are not like this, as they have a fulcrum design. For more on the difference between collet vs. fulcrum designs do an online search.
As far as I know, the spring-action Regal is the only design that allows you to go to different hook sizes without making adjustments. Not true rotary, of course, but the die hard fans will tell you that is of no importance, and since you only have to please yourself, that is 100% accurate.
