Since you asked for opinions here is mine. Not a fan, weekend events just work better for me with a M-F job. If you already have Sa/Su off, a weekend event may only mean one day off, at MPFB my roommate didn't have much vacation, and left a bit early to ride down Friday. Usually one day is enough, unless I want more riding then I use 2.
I agree with some others, if you're doing a new event great. I think changes to existing events need to be more carefully considered (starting with the organizers and regular attendees).
MPFB is already a week long event any idea how many come just for say the first 2-3 days because it works for their schedule? Do you have some numbers for that?
Are you hearing from members that want weekday rallies, or is it just part of the "lets try something different" plan.