Lester,
I towed a 2000 Grand Cherokee (same parts and installation as 2004) for 4 years with the M&G system. I loved it. I am now towing a 2005 Grand Cherokee that I transferred the M&G cylinder to when I purchased it. The installation on the 2005 was a little more complicated than the 2000 was because of the clearance issues on the 2005, but it was not to hard.
The hook-up and disconnect each take about two seconds and the system has performed flawlessly for all of the years that I have been using it. It requires nothing from the driver except to plug in the air hose. The air brake on the car works just like the ones on the coach.
If you are not mechanically inclined, the M&G factory in Athens Texas will do the full installation for you at a reasonable price and they do excellent work. In my opinion the M&G system is one of the best, if not the best supplemental brake on the market for a coach with full air brakes. If you do not have full air brakes (like the air over hydraulic on some Beavers), there are probably better matches for your coach.
Gerald