Well I mix my own for two reasons
1) The stuff is always fresh in what ever amount I need. I mix mine up just before loading the film tank.
2) I know with a stock of chemicals I can mix my own no matter what.
I don't use the bleach in the formula but others are and seem to be doing fine.
On the patent issue. Does anything really require Kodak to be 100% honest in those patents? If they patented a formula that was close to the right formula would that be okay? Can you even patent a formula? Isn't it just the process?
To be honest I find the effort to mix the C-41 film developer trival. No more effort then mixing up various parts of a kit. Once I got over the MSDS for Hydroxylamine Sulfate mentioning the stuff goes boom I've been okay.