Well, I answered this question today. Installed 25mm rear, and 15mm front HR spacers, and noticed a DRAMATIC difference in looks. Drove it just for few miles, but did not notice any diff in driveability. I live in the boonies (AZ desert), and going with 20" wheels was not an option. I need the high sidewall tires, so I decided to keep the wheels stock (18" with Bridgestone RFTs), and bring them out a tad. I also have the flares on order, but I'm not sure at this point whether I will install them (I like this look that much!).
I also put Shnitzer dual exhaust tips, punched out the bumper (mine is a flimsy 3,0!), and debadged the thing (those emblems collect too much wax, sand packs onto that.....). I know you'll all scream for the pics, but I don't have any at this time (maybe next year!).
The point of the post is not bragging, but to tell the fellow "enthusiasts" that are still on the fence about the spacers, to do it. You'll love it. Go with the reputable brand, hub centered and light. Installation is a cinch, and the thing even looks lower, as the wheels come out. Cheap mod that makes "the thing" looking hot. (I refuse to call my X a "truck", a "car", "SUV" or "SAV" - it's none of the above - ergo - it's a "thing" and a great driving/looking one at that!)