The signal sent from the satellites is the same and reception quality has more to do with the dish and LNB installation than the STB used. There should be no practical difference between the Picture Quality from a standard SKY digibox and SKY+ however due to different components and manufacturers it is not out of the question that a SKY+ replacing a digibox may to a viewers eyes produce different PQ, could be better or could be worse, depends
Hmmm. I've finally got round the s-video socket on my std sky box...i scart to my dv220 dvd recorder then out via s-video to my processor and then to plasma, the picture quality is pretty good but not as good as the direct feed from the sky+box... still gonna need sky + i think.