Perhaps you didn't read my post. I do play the Japanese mixes. Were you under the impression that there were 7 mixes of USA? Did you think that USA mix has boost and solo options? Did you not notice the part where I said USA mix sucks? As fully explained, I only play USA mix because I'm stuck where it is for half an hour, and it is the only game there worth playing. The only other DDR machine in the vicinity is the 5th mix machine that I can only play on Fridays because the location that has it closes at 5 on other days. As previously stated, I wasn't playing a whole lot of 7th mix because I was a lot more interested in the Dance ManiaX machine in the same location.

Since you obviously don't know as much as you think you do, I will reffer you to this page for enlightenment:
http://www.konami.co.jp/am/AM/list.html