I have Blue Ox towbars and baseplates as well as M&G Tow Brakes on both the Wrangler and Cherokee. The M&G is without a bet the best tow brake system around and after having played with 2 others I'm sold on M&G. The M&G fits between the brake master cylinder and vacuum booster and is a failsafe setup. One drawback is that you need air to run it. If you have a gasser, you need to buy the compressor kit and that gets pricey. On a DP that's not an issue however. On some toads there isn't enough room to move the master cylinder forward to allow for the M&G module. On my 2005 Wrangler it was pretty easy. I just relocated the cruise control vacuum operated cable actuator down to the area beneath the master cylinder so I had plenty of room. On the new 2007 Wranglers ther's all sorts of traction control stuff that would preclude using the M&G unfortunately.
Blue Ox makes great towbars. I had the Aventa II originally and now have the Aventa LX with the spherical joint. Both were great towbars. The Grand Cherokee has removeable tabs, wehich are a real sweet feature. My Wrangler had the standard fixed tabs but I understand that Blue Ox will be coming out with a removeable tab baseplate for the Wrangler, although I don't know when. I'll probably weld a set on mine anyway. I have the factory off-road bumper with winch mount so I did have to do a bit of grinding on the driver's side mounting flange where the off-road bumper and baseplate had a bit of interference when trying to bolt to the frame. Following is a shot of my setup up on Red Mountain near Ouray, CO. The white stuff packed into the towbar is snow - after all it was June.