I looked at that option and found a product on the market that was basically the same thing- Just softjaws bored for 5c, and a plate that retains the collet and sets the depth.
Nub Tools Master Jaw System for 5C & 16C Collets - Penn Tool Co., Inc
They want like $800 for it, so I set about designing my own. I think I have it sorted, but honestly I just ran out of time to make the collet sleeve, bore the jaws, and hope I got it right on the first go (which I certainly wouldn't. If their product was about half the price I'd have just bought one. The Kalamazoo collet chuck (the one on mcmaster) existed, was cheap relative to my time, and was here the day after I ordered because mcmaster is magical.
If I were going to spend any more than that and I'd just drop $1200-1800 for a proper Royal 5C chuck that mounts on the spindle face and uses the hydraulic actuator, but if I am going that far I may as well buy a QG collet chuck for the wider gripping range and super fast collet changes (like $2800 for base model), and if I am going that far I should get the dead length version (add another thousand), and then I need collets at some $250ea, and and and.....
The Kalamazoo chuck is dead length (there's a sleeve that moves forward instead of pulling the collet back), it's easy to adjust, it gives me a couple of extra inches of projection from the front of the jaws (good for clearance when working on small parts), and it just tightens with about 1/3 of a turn on the cam lock screw. And I already ran a couple hundred parts and more than paid for it.
So to each their own, and if someone finds a set of 5C collet jaws for less money (Or someone makes a working set and is willing to share the CAD files) let me know. Til then I can totally live with a half turn on a hex wrench for my type of work. Hmm, I wonder if I could put a hex in a live tool holder and automatically clamp and unclamp......that's a terrible idea, heh.