I can't speak to the CDCO vs Shars, but my guess is that most of the generic chinese toolposts are made by the same company, or are at least pretty similar in quality, which is to say, not very good. Some have had good experience with them, but I think one of the issues is the inconsistent quality, so it can be a crapshoot.
A wedge toolpost is better than a piston toolpost. Aloris used to make piston toolposts, but they don't any more. That should tell you something.
That said, the generic chicom wedge that I had wasn't as good as my Phase II piston post. If you can't afford an Aloris, get a Phase II. You can get generic toolholders, but do yourself a favor and get a Phase II wedge toolpost. If you have to buy one and replace it, it will end up costing you more.
I switched from a Phase II piston to a Phase II wedge and I like mine. The piston post didn't lock as well.
I have a pile of CDCO toolholders. They are adequate, but, get yourself a box of holo-chrome or other USA made setscrews. The ones that come with them will raise your cholesterol level because they are made of butter. The main difference you will notice with the CDCO and other generic toolholders is that your handle will lock in different places due to inconsistencies in the dimensions of the dovetail, but they will still work.
You can buy better tooholders, but you will end up with fewer for your dollars. If you find yourself having to change toolbits in your toolholders, then it ain't quick change.
You can get 5 CDCO toolholders for what one Aloris costs, and 3 for what a Phase II costs (with some change left over).
Also, for a buck more (from CDCO), get some of the turning and boring ones - they have a groove in the bottom so you can use them with round boring bars as well as square toolbits. Get some of the turning-only ones, because sometimes you have a square bit that is too small and drops into the groove.
If you can't find a new Phase II on sale, look for a used one on ebay. You can buy new Phase II axa sets on ebay for $200. A used set recently sold for $125 on ebay.
Steve