As far as I Know, the twin select range is an inferior range using thinner blades and cheaper handles. they're not bad at all, after all they are Henckels. also, as far as I know, the Henckels 4-star range is the same as the 5-star range except they don't have flashy ergo handles. I don't have a problem with trad handles though.
the advice therefore is to spend the extra and go for the top range knife, it will make a big difference, and $80-90 isn't the end of the world. I use an eight incher (20cm) and it is perfect.