RB: more Filter Options on intelligent Playlists

Hi, 

I would like to address again a needed feature/option that relates to smart/intelligent playlists in RB. 
It would be very helpful if int. playlists had the option to build a match with other playlists. 

for example: Playlist IS xyz ; Playlist IS NOT zyx (same as in iTunes)

I would be very happy if this function would finally be added to the program. Please rate up if you agree!

Thanks a lot!