Finally I have managed to nail down a comparison video between the two galaxy s4 versions..i9500 & i9505.
https://www.youtube.com/watch?v=Wt5im3WAZYc&feature=youtube_gdata_player
Basically it seems that the octa version is marginally better on batterylife and beats the snapdragon on most benchmarks except graphics.
Although it appears that sgx 544mp4 is able to pull out better frame rates in some current games, as indicated by gl benchmark 1080p egypt...adreno 320 seems to be faster on benchmarks that simulate heavily shader based games that may come out in the future.
660ms on sunspider is very fast..still side to side comparisons between the two in the video show no discernible difference in performace, whether that be app launch or web browser...only the flight game showed a lag on the snapdragon.
More puzzling was the lag shown in the video on both devices going through the touchwhizz UI, I flagged this up some time ago and was shot down because of pre release hardware, here it is clear to see in shipping products.
As it is clearly nothing to do with hardware performance this must be some kind of software bloat on the touchwhizz, any more bells and whistles from samsung and there might be a danger of touchwhizz turning into the laggy bloated mess htc UI carried untill the one x.
Edit: Here is the article URL.
http://pocketnow.com/2013/04/30/galaxy-s-4-octa-vs-galaxy-s-4-quad-video