I traded in my 06 taco 4x4 AC, with every mod you can think of (except the supercharger) for my new 07 FJ. While I did bite the bullet on trade (they only gave me 19500 for my taco), it was worth every penny. I loved my taco...miss the utility of a pick-up, but the ride is better, the whole family fits in it comfortably on long trips and it's the same engine I had in my taco. My only gripe on the FJ side was the compass/thermometer. I got used to having it on my taco, but it was part of a $2500 upgrade...it couldn't be ordered seperate. As far as 4 wheelin' goes...the FJ goes places the taco couldn't, I think partly to the added weight allowing it to grip instead of slip. Mileage is about the same (not gotten better than 15-16 on any tank yet, regardless of driving conditions). Hoping that changes after a few thousand miles when things start lossening up a bit. Haven't made any mods to it yet...wallet is still a little light from all the mods on the taco. Going with AFE CAI, JBA headers and catback system. Haven't decided on whether or not to lift it, if I do, it will be Toytec again. As you'll find searching through these forums, FJ owners are just as die-hard fanatics about their vehicles as tacoma owners are. There is another forum site dedicated soley to FJ's (if you haven't already found it) that has a wealth of info. http://www.fjcruiserforums.com/forums/
I got hooked on Toyota Nation when I had my Tacoma and it has served me well. Not trying to pull anyone away from here, just throwing it out there. Hope you decide to come over the the dark side...you won't be disappointed.