Make sure you run that pedal through the ringer, and take a backup for a month or so. I had one, and really liked it, until it just stopped working all together on stage. Fortunately I keep a backup in my toolbox. I've heard a lot of good reviews of those, and I love GFS, I've used about a dozen sets of their pickups, and replaced everything but the wood and frets on an LP copy I rebuilt for a friend, but my tuner died in about a month.
I will say that GFS has been really cool about it though. Unfortunately they were out of stock when mine died, so they couldn't replace it, but I'm getting store credit (yay new tele pups!). They have a one year warranty on most of their products, so it was a really no questions asked situation.
Anyway, good luck with it, hopefully I just got a lemon (likely the case).
I had Nashvilles in my 5120 for a while, they sounded good, just not what I was looking for. I would advise however to spring for the coil tap pots when you install them. That gives you an enormous amount of tone options.