If there is such a gripe about the "value" you paid for the system a year ago, think of it in terms of what was available a year ago...
What would most people have paid a year ago for the equivalent system you are about to receive. Since you paid $3400 for the GEN2 system you have, what would any enthusiest have paid for your system? 4000? 4500? The bottom line is they are replacing your system with something of equivalent or greater value (depending on what is available) and you're not getting screwed out of anything.
The only person to blame is yourself, for not being more aggressive with Dell when you began calling them and going through the "trouble ticket" process. The way I see it, is if there was a major problem with the system you originally purchased and it took you a year to get it resolved then it doesn't sound like a major problem as you have so stated. If you break your arm and wait 6-8 weeks to go to the doctor and then have the nerve to get MAD at the service he provided because it didn't heal right, who's fault is it?
Sounds like you are just blowing steam that Dell isn't spending "$3400" on the current system technology to replace your system. I have a XPS GEN1 system that I use daily. Back when I got my system, I had a keyboard issue right out of the gates, however the problem was intermittent (sometimes on a hard boot up, it wouldn't work correctly). I called Dell one night. Spoke to a tech, went through a few things (ran diag CD prior to calling). Got an error code, gave him the code (which didn't amount to anything keyboard related). I said that the Keyboard was the problem, if it could get replaced, that would make me happy. I got the keyboard fixed within 2 business days (sent out to Tennesse and returned). Keyboard was replaced, i was happy and the system worked like it should. End of my happy tech support story.
My point is that I had an issue with my system, stated what I would like done (within reason) and was very satisfied in the end with the Dell support staff. When you deal with people like a civil human being, they tend to treat you like another human being. Amazing huh
If you call in right out of the chute saying how they should replace your entire system because "it doesn't work right" then you've got to give them reason to believe or know that it doesn't work right, then you play their game (and yes I know lemon's do exist and would need quick replacement). Never let it stretch out into a year long process as it damages your credibility within the Tech support staff if they see tickets a couple of months apart. You want those tickets to be close together and it helps build your credibility with the upper management at Dell. who make the decision to do a machine replacement.
Just my nickles worth in this ever lasting thread.