Can I ask you a question? I had the same situation - I took a ph impedence test while on PPI's as instructed by the dr., to see if they were working b/c I also had no change in symptoms (they were still there).
Mine also came back that they were doing there job, but the doctor didn't tell me "you have significant amounts of non-acid reflux". I did see on the results though, that my non-acid reflux was 'high'. It was like this:
acid reflux, 11 (normal 55)
weakly acid reflux, 21 (normal 20)
non-acid reflux, 8 (normal 1)
all reflux, 40 (normal 73)
Do you happen to remember your results? I would think my LES is working if my total reflux events were almost only half of what was designated as normal...but I did have 8 non-acid reflux events (compared to the norm of only 1)...
I've been confused about this over a while and saw your post and thought you may have experience.