A friend of mine had a 2004 and I think a 2006 both autos.  The transmissions aren't an issue.  The 42RH is still stronger then the NV1500, AX5 and about as bulletproof as the 30RH/TF904.
The 2.4L is fairly durable.  I haven't heard of any problems with it.  The engine was used a far back as 1995 in teh Dodge Stratus and used as the basis for the forced induction SRT4 and Cruiser GT which have a pretty dedicated following.  The Liberty used it from 2002-2006.  There are a few members who run the 2.4L here.  Art has a manual...