In the year and a half since I first got the SAS NF to make this comparison, I have played and gigged a couple more NF3s and another SAS NF, so I have a better feel for the differences between the two. The only thing I'll add to my description above is that the NF3 can produce a really nice sparkly/"chimey" sound with the volume rolled down, especially in positions 2 and 4. I could not get the same sounds out of the SAS NF. I suspect it's a result of the different scale lengths of the two models (25.25" vs. 25") but that's just a guess. Maybe it's also the korina vs. swamp ash.
I end up playing my NF3s more often because of that extra versatility and also just because I prefer the feel of the Strat-like body vs. the typical PRS body.