I've used GE for six years, and it's getting to be more hassle that it's worth, especially entering EWR and JFK. It's fast, yes, but as a 'trusted' passenger CPB are really pushing their 'zero tolerance' approach to customs declarations.
For example, a few months ago I was given a massive lecture and a 'final warning' for not declaring a chocolate bar. I was told that I'd lied to a government official by not declaring the food item at the GE kiosk, and that I was lucky not to get fined.
I was also told that as of 2016 GE 'final warnings' are over, and it's now 'zero tolerance'. So now, I no longer click 'no to all' if I have any food item on me at all (chewing gum, candy etc), which means you get the black 'X', which means standard screening.
I also saw a woman given a 100% duty fee for not declaring a coat she'd bought in LHR Duty Free (and which she was carrying in a Harrods bag, not hidden in her luggage). The coat was over the $800 limit, and she made the mistake of ticking 'no to all' at the kiosk. The CBP official didn't believe her when she said that she was not aware duty free items in transit had to be declared, and that she was lucky not to be fined on top of the 100% duty. So in effect, she paid twice for one coat. She also had her GE status revoked immediately ('for ever'). How do I know this? Because the entire conversation took place at full volume.
The other thing I've noticed since January is that GE pax seem to be subject to EXTRA questioning at customs (i.e. once you've gone past immigration): "did you buy anything abroad, do you have food in your bags?"
As far as I can work out, with the paper forms they don't mind you filling it out again if you've made 'a mistake' and you just pay the 3% duty (for example). Once you've ticket the boxes at the GE kiosk, however, you've effectively made a sworn declaration, which they will use against you as leverage for a higher duty rate, or a fine.
The TSApre privileges still make it worthwhile for me.