Any Pathfinder or QX4 older than 2001 will have only 170hp. It will be important for you to test drive a 2001 and then a 2000 or older to feel the difference. The QX4 is basically the same thing as the Pathfinder, except it has nicer accessories and body trim. It has lower profile street-biased tires and wheels, also. Aside from the luxury trim, one of the nicer things about the QX4 is that it has a full-time transfer case with a 2.569:1 low range.

A leather-clad QX4 may be nice, but leather gets hot in summer (especially if the exterior color isn't light-colored) and it will never compensate for the lack of HP. If you get an R50, get a 2001 or newer, or get an X. Just my 2 cents.

And since you mountain bike a lot, you might want to also consider getting a trailer hitch and a hitch-mounted bike rack (since lifting a bike onto the roof is a pain the butt).