Amquel vs Amquel+

I went into a LFS the other day looking for Amquel+. The guy (kid) tells me
that they don't carry Amquel+ becuase they don't like it (no explanation),
but they do have and like Amquel. ???? So I scratched my head and left.
I'm not sure, but I thought the difference was that + also removed nitrites
and nitrates, so how could that be bad? I've been using + for around for
years to condition water at water changes (homemade python, add water direct
to the tank and appropriate dosage of +), and all seems well. Opinions??