Tours can be done with any good bike. I just got a LHT last week and absolutely love it.

THis said, You don't _need_ a LHT to tour. If you can get one, I think (as well as many other people on this forum) it's a great bike for the price. The other ones you mentioned, while more expensive and, I assume, somewhat better in certain regards, but the fact is many people have pedaled from ocean to ocean with much lesser bikes than a 520 or a LHT.

Heck one guy did it on a BMX sitting backwards. Yes, he was supported, but still...