I have listened to my mate's N802 driven by Conrad Johnson tube monoblocks. He previously used a Mcintosh MC402 with the N802s and didn't like the result too well, too laidback and flat sounding according to him.
Personally I think it is difficult to advise on the 803S vs N802 even though one may be very familiar with both speakers, since the speakers may sound differently in a different room with different electronics, not to mention dissimilar listening preferences. One may feel the N802s to be superior to the 803S in his room with his amps(that if he managed to compare the speakers side by side), but another person may feel otherwise in his own room together with his own amps. As most have mentioned here, the amplifiers play a major role in making the B&Ws shine.
Personally I prefer the N802s shape more than the 803S. Sound-wise is another matter.
FWIW I find the bass of the N802s(in my friend's setup) to be pretty loose and doesn't go too deep. Possibly due to the room and amps. Great sounding speakers nonetheless.