i had the same question to answer . But went for the 6900HD because of the HD yes it is a lot more money(double) but yu do get HD satellite and HD freeview (when it comes. plus offcourse freeview. Okay the 6900 is a bit ott.
especially if yu dont have a HD tv or a screen bigger than 32 inches.
if yu can survice without HD then the 5000 series is a better choice.
lucky my wife paid for it. the HD is surperb just not enough channels on 28 E. i only get three channels. so far ch4 hd is not fta/v ITV is crap ! 19E is ok though. i get discovery and several german HD channels films and footie the main problem there is 900 plus channels (tv) so not really had a good look yet.. (19E)