Jodet, I too have a bit of an issue with the Model 6 pricing too. Bearing in mind I have not heard it or directly compared it to my Model 4, I find that it would indeed really have to bring an awful lot to the table in order for me to double the price of my 4's for the 6. I am thinking it would be better to leap-frog the 6 and go for the Model 8, seems to be a bit more substance there for the money. But again, listening and all that would tell the tale, not just my own thought on value/pricing.
I feel I got a good deal when I bought my Model 4's, they were just being imported into the US at the time, and I was first onboard with my pair here. Got them for $1595/pair. Not too long after, once the new dust settled with distributor pricing etc., they went up to 2K/pair, and all the other models too shifted upwards. With that being said, I do think the 4 is a very good buy, providing one likes what they bring to the table to begin with. To my ears, it is a solid little performer, and one I don't think I could easily replace with much else.
Sorry for the slight diversion, back to the OP now....