I've got both. Although I really love it, my 2006 Liberty CRD has been nothing but a money pit. I have spent well over $6500 on repairs in the past year. It had 71K miles on it when the timing belt broke. $5600 to fix it and I even purchased the lifters and rockers myself (from wobbly, a Lost member). Part of that cost was for a new turbo and both cams. That was 3K miles ago and it's now back in the shop for an unknown issue, won't start???
Just last weekend I purchased a 2007 Grand Cherokee Limited CRD with 40K miles on the clock.
Haven't had it long enough to get a real test but so far it outpreforms the Liberty by every measure. The ride is much better and the Mercedes 3.0 V-6 is a real powerhouse and hopefully a better motor. I got 23+ mpg on the 450 mile trip bringing it home running 75-80 mph. I never got that mileage from the Liberty even though it's a 4 cylinder. Some Liberty owners claim 30+ mpg but I think they must be smoking something, I don't think it happens. The one thing that gave me a shot in the wallet is the oil that is recommended for the 3.0. I went to 5 places before I found someone who carries it, then paid $8.95 per quart for it. It takes 10 quarts for a change! With filter that makes it a $100 oil change if done myself.
I'll probably keep both although I have a problem trusting the Liberty after having to bring it home on a rope 3 times in the last 6 months.
This forum is full of great information on the Liberty and there are some very informed folks here willing to help but there is very little information on the Cherokee.
Hind sight is great and with what I have experienced I wish I had purchased the Grand Cherokee crd first and never saw a Liberty crd.
Which ever way you decide to go ~ good luck.
