I was making a similar choice of LHT and 520 without the discount. I had a bias going in as I had ridden Treks and the company had also been good to me (longer story). Back then, I could not find a LHT to test ride. I did not want to spend that much money without the test ride. So, I bought the 520.
I now have thousands of miles including the southern tier, a ride from key west to Milwaukee, N. Sea in Europe, and many more on roads and unpaved trails. I have been very pleased. I would change the saddle before your first ride. And, the tires as well which only gave me about 1,000 miles. Obviously, if they have changed these features from my brownish (I think they might call it cola) color bike.
Good luck with your decision. From what I can tell, having discussed and research your question, you can't make a mistake between these two bikes.