Since a few years already now, we're doing packs off take-off in our company as an SOP.
It's really no big deal. I don't see or feel any abnormal cabin climb rates after take-off and when switching on the packs with 20 secs interval, there's no discomfort to pax or crew either.
It's really no big deal. Many companies do it and it does save on engine wear, maintenance (and probably fuel as well)