Rick, the truth is, you're right and I have no idea why your LFS would
like regular AmQuel and not AmQuel +.

Both AmQuel and AmQuel plus have the potential to cause a pH crash if
your water has a low KH level. But since they both can do this regular
AmQuel is no better then AQ+. If you have good buffering capacity
already then AmQuel is a great water conditioner (my personal favorite)
and AmQuel+ is great with a little extra goodness sprinkled on top. At
my old house my KH was extremely low so I opted for Dry Buffered
AmQuel. For me it worked just as well as AmQuel and added the extra
buffers I needed.

Oh, for those that don't know, I should point out that AmQuel or
AmQuel+ alone is not a complete water conditioner. Both should be
combined with NovAqua.

If you ever find out why they don't like AmQuel+ let us know. My
curiosity has gotten the best of me.

-Christie