Parent's comments have everything to do with the parent's employer and nothing to do with the actual 9/80 schedule.
I've been working 9/80 for over 5 years now. It's a great benefit for me. The extra hour isn't even noticeable after you've already been working 8 hours. And when you can bail an extra hour early on the on-Friday, you feel like you got a little bonus.
Getting stuff done during the week isn't much of a problem. The grocery stores are less crowded in the evenings. Any "business hours" business can be conducted on the off-Friday, or during your extra hour on the on-Friday if you start early enough.
Insist on flex-time, however, that goes for any schedule, not just 9/80.
You will become spoiled by the 3-day weekends. 2-day weekends don't seem long enough.
As far as management respect, don't work wherever the parent does, obviously. My customers don't care that I don't respond on an off-Friday, because they're off too.
Questions/issues may include:
* Will all employees be on the 9/80 schedule (and will they all be on the SAME one)? If some people are not allowed to do 9/80 (e.g. hourly employees), are they going to be resentful?
* How is overtime handled on the off-Friday? For example, we have a certain number of hours of OT that are automatically unpaid if they are worked on an "on-day". But if they are worked on an "off-day", including an off-Friday, the mandatory window can be waived.
* Can you switch on and off of the 9/80 schedule at will?
* How will your timekeeping be handled with the different-length workweeks? Our work week is cut down the middle of the Friday to make each "week" 40 hours and makes time accounting complicated.
tl;dr - 9/80 is great. Do it.