The Weber Legend series (models beginning with WLE or WLG), now renamed Weber Traditional (W), was exactly the same as the Young Chang Traditional series. The Weber Sovereign series (WSE, WSF, WSG) was the same as the Young Chang Professional Artist series, and the Albert Weber series (AW) was the same as the Young Chang Platinum Edition.

Do I just buy the Weber because he likes it better?
Do I ignore the difference in resale value? (If the difference is only $500 at the end of five years, then I'll buy what he enjoys playing the most. But if it is $2,000, I'll have to rethink that.)
Is any difference in reliability going to be significant?
Are both pianos likely to have a similar life span of usability at his level of play?
Are there other pianos in this price range that I should have my son evaluate?

He said, he didn't care who made the piano, he's just interested in the sound

Thank you all for you very, very helpful and thoughtful comments. Everyone's comments helped me.

While there are some differences of thoughts on pianos -- a clear message I picked up is to go with what my son likes (and that I should consider getting him a grand piano). I also really appreciated the comment that the K2 got “brighter” over the first few years. Although I should rule it out since he doesn't like the sound, that comment helped me completely put it out of my mind. While that sound is obviously enjoyed by a lot of people based on the sales, what he disliked about the K2 would only bother him more as time goes on.

I estimate he has tried at least 35 or 40 different used and new pianos (mostly used ones). He probably is ready for a grand and has said he'd like one – as he likes the ability to control the sound more (whatever that means). That is an excellent point that it is a buyer's market for grand pianos right now. Unfortunately, I just can not afford to take advantage of that. I'm stretching to be able to afford the $4,000 for the Weber. (My two cars recently were hail damaged – and the only way I can afford this piano is to use the $1,000 I was going spend on the insurance deductible for the piano. I would prefer they didn't look so dinged up, but it doesn't affect how they drive.)

I suspect everyone is right that he'll outgrown the Weber in a few years. But, I'll just have to cross the bridge for a grand piano then. I feel that he has so totally outgrown the old 40” Currier he started with 7 years ago that I need to do something now so he doesn't get frustrated. The Weber probably isn't a big of a step up as would be ideal (and I'm concerned it is called an “entry level” piano), but it is the only piano (new or used) he's actually liked that is under $6,500. And, he “really” likes it. (Maybe I should not be concerned about it being entry level if he “really likes it.”) He's been very good about knowing what I can afford, and said the improved feel of the $6,500 piano wasn't worth the extra $2,500. (He really liked a $76,000 Petrof grand at one store! He tried a Kawai grand today and said it too has the Asian tinny sound that he doesn't like. He said he still liked the Weber better. Fortunately, he gets to play a mid-size grand at our church each week, and occasionally gets to play the concert grand there.

I called his piano teacher after reading the replies. She said a lot of her students have Yamaha and Kawai pianos, but like my son, she doesn't like the sound of them as much as other brands. (I guess that's why my son really likes her as a teacher – they have similar preferences.) She knows the store where the Weber is. She suggested he try another brand there (some German brand that starts with the letter P, I think). Turns out, my son said that's the $6,500 piano he also liked. She basically said that she thought the price of the Weber was a fair / reasonable price and that my son knows enough that if he really likes the Weber, to get that one.

Thanks again for everyone's comments. Between your suggestions and reading the other info on this website, I've gotten quite an education the last several hours! I've forwarded my son a link the website. I'm sure he'll like it also.

Fortunately, he gets to play a mid-size grand at our church each week, and occasionally gets to play the concert grand there.

You're buying the piano for your son, NOT your tech.
If your son prefers the Weber over Kawai or Yamaha then that is the piano that he should get.
The preference in piano sounds is highly personal.
For example many players love the Yamaha sound whereas there are many (myself included) who simply do not like the Yamaha sound and would not be happy with a Yamaha piano.
The same goes for Kawai, or any piano brand for that matter.
Heck, it is even applicable between different instruments of the same make and model.
Sometimes a player will just come across a particular piano that really resonates with something inside him and he falls in love with it.
THAT then is the piano to get.
In fact your son is lucky to have found something that really speaks to him because many of us never come across a piano like that (well, not within our price range anyways).