ALRIGHT! Finally able to respond and hopefully I can clarify some of this. The chuck is absolutely the issue, during a setup about a year ago, the program re-called a tool to change its offset, but this was not properly updated to reflect the turret. Both the programmer and I missed it so it indexed straight into Jaw 2 and said jaw has been a bit weak ever since.
The smallest tolerance I have to hold on a diameter is +.0.0 -0.0004, which is about equivalent to an H6 tolerance in Metric GD&T. I need to keep concentricity between setups as mentioned above. Runout is nowhere near as tight as +-.0002, although I think it can be safely assumed that would be a nightmare on a hydraulic chuck, rather I need to keep it within +-.004 and the chuck, between ops can really push that, plus the chamfers look like garbage and no one wants that.
So I was tasked with shopping for a chuck, and thought the S-20 was the right way to go and so far I haven't found a straight forward product that best suits us. Our budget is not so tight that we can't afford a new one, but none of use think purchasing 30 new collets (about $9000) for a Quick Change from Royal or Hardinge is worth the investment. We would be better off spending that on modular tooling on the lathe. The standard S-20 chuck cannot be used with a solid stop for the chuck, but if you buy a dead length style, they can be, OR you can purchase a quick change chuck and then purchase the S-20 master collet for it. All of this requires spending extra money of course.
In general, while all the brands do the same thing and have more or less similar jaw sets available, they are not interchangeable between brands. (I believe Nova, Record, Sorby, and Patriot may be the exception here. Anyone care to clarify?) Therefore, you are likely to stay within one brand or another. (Think Nikon vs. Canon - good quality, doesn't really matter which you choose, but you can't interchange lenses.) That being said, Nova provides a solid product for a good price. As a new turner, that's a good combination. I started with Nova, and they have served me well. Unless you are doing really big stuff, the SuperNova 2 can handle most anything. That being said, I came into a used Vicmarc 120 recently, and it is noticeably beefier than the Nova, and as noted above, has a remarkably wide excursion before you have to change to smaller or larger jaws. So at some level, it depends on how hard you plan to push your equipment, and how the stuff feels to you. For some, the Nova level stuff feels fine - for others, it feels slight. Conversely, the Vicmarcs (and the like) can feel smooth and solid and well built, or they might strike you as overbuilt and overpriced. No right answer. Choose what fits in your situation and don't worry about it.