Ryanjsoo has a review of the latest iteration of the HifFiman RE-600 on Head-Fi. From the review the RE-600s appears to be a worthy successor to the 600 and can be found for less than have the price of the original. Read the extensive review by clicking the link below.
Pros – Linear tuning, Fantastic fit and comfort, Great isolation, Sharp imaging, Clean midrange, Nice bass extension
Cons – Treble not aggressively detailed, Stiff non-removable cable, May be too mellow for some