At the end of the day, everyone has their opinion as to which years and engines were better than others. If this is the truck you want, don’t let their opinion stop you.
A used LR4 is still a used vehicle. Even the well cared for vehicles have issues, but then again, so do the new ones. FYI, I bought a brand new 2019 Honda Odyssey and the darn thing has left me on the side of the road twice in less than two years! The funny part about it is that when I told the folks at Honda I had a Rover, they said, Rover’s were nothing but over-glorified paper weights…then I told them my LR4 has NEVER left me stranded. But, I could vent about Honda for a while, so back to the topic at hand.
Sounds like you’ve done your homework. As I said before, cut the filter and check for metal, heck, you can even send an oil sample off for analysis and it’ll tell you exactly what’s going on inside that engine block. I used to do it for my aircraft engines because the FAA directed it, but then I started doing it for my trucks as well as it’s a great indicator of internal wear or issues.
I think if the seller is willing to swap the timing gear, and you check the filter or have the oil analyzed, you’ll have a pretty good idea what you’re getting. As with anything though, nothing is a 100% safe bet.
FYI, it might be worth swapping the injectors while you’re in there, it’ll cost a little bit, but I’ve seen some injectors fail after they’re serviced (aka removed and reinstalled). Don’t ask me why they fail, cause I have no idea. It’s just a thought, but not a requirement. I should also tell you I tend to “over-repair”….just in case.