I had the chance to directly A/B these very two sets in a showroom of an EMG dealer, in similar guitars. The difference was quite a bit, and the EMG dealers were converted. They were blown away, really.
You probably know what I think of them personally, I'm just trying to relay the third party reactions for you. Everyone else felt the EMG's were flat and dull by comparison. The 57/66 are much nicer sounding/feeling than other EMG's, I'm not knocking them and if you go with those, you will have a nice sounding guitar. With Fluence you'll have 2 voices, the ability to coil split if desired...