I don't have experience with the new Explorer, but I do have a 2011 Ford Taurus SHO and the Explorer shares the same platform as the Taurus. I really like the 2011 Taurus. I traded in a 2007 Infiniti G35 for the SHO and there is no comparison, the SHO is more comfortable on road trips, gets better fuel economy, is quieter, and it has a lot more creature comforts for less money than the G35. So far the SHO has had fewer warranty and recall issues than my G had in the first 6 months of ownership.

Interestingly, I also have a 2004 Mountaineer and the Taurus exterior dimensions are quite a bit larger than the Mountaineer. The new Explorer may look smaller than the existing one, but I don't think it is. Since the new Explorer is based on a car platform, it doesn't have a full frame and probably won't be as good for pure off roading, but it doesn't sound like that's a concern for you.

My sister in-law has an X5 and it's been quite reliable for her, but maintenance costs and parts (such as side view mirrors) are very expensive.

-Rod