JD cutters are made by a company called John Deere & Co. at their Welland Works, in Ontario Canada. MX Series cutters are all in house, LX cutters use a JD designed gearbox that is made elsewhere.
The JD cutters do cost more, but include safety shields and a slip clutch which are extra cost on most others. Add those and compare quality, and suddenly the TSC stuff isn't such a great deal.
The 4120 really needs the slip clutch, you will break shear bolts faster than you can replace them. You really want the safety chains. The cutter can kill you throwing rocks and spears at you.
Finally, Deere usually has great incentives to add a cutter to the tractor, so you can often save some that way.
Of course, you will be most certain that the green one will work with your iMatch.
I couldn't be happier with the performance of my MX6. They cut like crazy, are fast and very clean. I have even had to use mine as a finish mower with better than expected results.