i just did this same thing 6 months ago. was looking for a newer family hauler DD/WW. at first i wanted a 100 series LC, but the gas mileage was terrible(^^ if you didnt notice any difference between the 07 taco and your LX470 then either you drove the piss outta the taco or there was something wrong with it. the hundys struggle to get past 14mpg, the 4.0 in either 4runner or taco should be close to 18+) and lifts were well not impressive. so i started looking for a 4th gen 4runner with the 4.7, not only were they hard to find(most who had them didnt want to get rid of them), but the prices they were asking were absurd. i just happened to stumble across the GX, and just glanced them over not even really seriously. the more i looked at them though, the more i liked them and the price was basically the same as the 4th gens, but you get so much more. as far as reliability or the electrical stuff going wrong, dont worry. there is nothing more to go wrong than with a nicely appointed 4runner, and lets face it, toyotas dont really have electrical issues, so put that fear out to pasture, as any failures you would see in a GX you will also see in a 4runner. we ended up with a GX and have never looked back or regretted it. the added head room is very nice. im 6'1" and i have a good 3-4" of head room with the seat in its highest adjustment. personally i think the GX is the better vehicle, it brings more to the table and honestly less options, so finding parts is easier -all GXs had the 4.7 v8, all of them were full time 4wd... about the only options where exterior/interior color, navigation or standard 6disc stereo(this is more desirable IMO) 3rd row seating or not, and KDSS or not. the only two trim levels were base or sport and only subtle changes like interior trim color and wheels were the difference. the 4runner had 2 different motors, 3 different trim packages, 2 or 4wd, or full time 4wd, 16" or 17" wheels, leather or cloth..... dont get me wrong im not saying those are bad, but when it comes time for replacing parts like brakes or other things those come into play and unless you know exactly what you have you could get the wrong parts and have that hassle. so in that aspect the GX is more simplistic, and more user friendly. i mean my wife can get parts for it if i need her to and she doesnt feel overwhelmed at the parts store or dealer. the only draw back to the GX is the suspension, it can be a tad more money to fix or replace if needed, but the good thing is both 4runner and FJCruiser parts will swap right in and are much cheaper! the 4.7l motor while yes having a timing belt as apposed to a chain is not a big deal really. belts have never been a issue in toyota motors, never have i heard of a belt failing on its own without something else causing the damage. its typically the water pump that seizes and snaps the belt, but the water pump almost always has been leaking for quite awhile before the failure and was ignored by the owner/operator. i have head of the 4.7s with over 200k on them and the stock original belt still in the motor. so the argument of chain is better is hogwash, and has no backbone, i can think of 2 or 3 negatives to chains right now so neither one is perfect.
having driven both and ridden in both and worked on both, i again say hands down the GX is the vehicle i would take time and time again. there would have to be a major price difference like $5k or more, or some serious issues with the GX for me to not chose it over a 4runner.
