Every time I read this forum it reinforces my theory that my 2009 Exp 4.0 SOHC V6 with 5r55 was built on a Wednesday. (if you work in the auto industry or know someone who does then you might appreciate that tongue-n-cheek comment). This Exp just rolled 285,700K on the way home from work today.
The biggest problem I've experienced with this vehicle is front wheel bearings and batteries. I've probably replaced a dozen front bearings and just replaced one of the rears for the first time at 280K. Probably on it's 4th or 5th interstate battery, just got a new one at Costco.
Engine is mostly original except for regularly maintained plugs, wires, belts and pulleys. Just replaced for the first time the starter at 284K, the timing chain tensioners at 277K, alternator at 247K and a set of O2 sensors at 188K.
I replace the fuel filter at about 30k, the tranny fluid and screen at about 100K and wix oil filter and mobil 1 at about 5k.
Only tranny problems I've experienced is a leaky torque converter seal (replaced during a fluid change) and a shifter mechanism breakage.
Because the miles are 90% highway, it's only on it's 3rd set of pads and rotors.
Replaced the suspension at 233K with a KYB kit.
I'm now seeing some weeping from the rear diff axle seals but not serious enough to see any spots on the floor or to get too excited about changing yet.
Other than the rocker panels rusting (I live in upper midwest with plenty of wintertime road salt) this is still a solid and reliable vehicle which I drive daily to the tune of about 800 - 1K per week in my sales territory.
I'm not drag racing this buggy but I do drive the piss out of it and sometimes wish it had more power for the times I had to tow stuff. Other than towing, it's got enough to get me and the family around town and cruise easily at 80-85 MPH on the interstate.
Based on my personal experience with this particular 2009 for Explorer I would not hesitate to get another one, especially with the mileage you indicated.
Good luck.