Very different products DP/VR-558 is recorders with 1st generation DivX/MPEG4 playback chip (can't play QPEL, HD resolutions , etc...)
While DP-608 is just player with hard drive (can't record) it will have when released 2nd generation HDef capable chip.
Btw: it's only my personal opinion but stay clear from KiSS unless DP-6xx mark real change in their aproach , I believe KiSS players are low quality , have a lot of bugs and low level of support. Also unreasonably high price - cost more then competitors while perform worse. Again it's just my opinion (after having DP-500 player that was OK besides some bugs and poor suppor and DP-558 recorder that was total disaster and I junked it after it died 3 times).