I was in my FLPS refilling my LC carboy and looked at the closing display. Big red-lettered signs were warning people "DO NOT USE CHLORINE TO CLOSE YOUR POOL--IT WILL DESTROY YOUR COVER".
I have used BBB sans borates in the summer for a few years now, but I have closed since 2005 using either the Anthony&Sylvan (my PB) or the InTheSwim non-chlorine closing chemical kits. These are pretty much identical, 3lbs. of MPS shock and an 'oxidizer' floater, plus some foam absorber gadget. I have had excellent results since 2005 (I let PB close the first year in case there were any problems and so I could see what he did.) I open to clear water and a clean pool, barely needs a vacuum.
I have been planning to switch to the TFP closing chlorine technique this year. I would appreciate any comments on the cover issue or non-chlorine closing in general. I have a healthy level of skepticism regarding pool stores but the issue does concern me. Thanks.