As much as I want LCD-3 and like joking, I don't think it's worth it to sell everything else (including kidneys :-D )... Common, those are just another pair of headphones. And even more, you have already excellent LCD-2 with their newest revision available for half the price of LCD-3 so why don't you consider those (if you do not have them yet)? Read Tyll's comparison between the newest LCD-3 and newest LCD-2.
I know that LCD-3 is better but it's rather a perfection of LCD-2 than whole new experience (their FR are extremely similar)... And in my opinion, your enjoyment of music and sound in general is much more important than hearing something a bit more perfectly. I would get something that suites your tastes with its sound signature and be content until you have large amount of money to spend on perfectioning your setup. LCD-2 are pretty much the way in my view here.
I think the HE-6 could go well... Its always good to have 2headphones that are atleast slightlydifferent and not having two almost identical ones :- IMO