Hi Andrew, we have a 2005 3.CRD Grand Cherokee, done 35,00o miles and tow a 1700kg t/a Delta. The Grand Cherokee is an excellent tow car at 215 hp and 525 of torque it makes light work of pulling the van, she will happily haul the van along at 60mph this includes climbing Sourton on the A30 in Devon. Fuel consumption is 19 - 22mpg towing, 24 around town and on a run solo have been able to squeeze 33 out of it. As for the box, the current range only comes in automatic, but it is regarded by the trade as one of the finest auto boxes available and the diesel lump is the tried and tested Merc V6. All in all the only machine that I would change it for would be the 4.2 Range Rover which is way out of my price range.
There are alternatives out there but most will have a straight 4 engine and a gear box no where near as smooth and reliable as the GC. Initialy we did have some teething problems but as ours was one of the first of the production line that was to be expected, however it has now setteled down and is an excellent , comfortable and reliable vehicle.
Go give one a test drive and see for your self acceleration of 0.60 in 9 secs and with the van on the back is almost the same as some of the competition solo.