funny you mention that. I was actually considering doing that. back when I would've only lost ~10h of progress it would've made sense but now....and now I can't beat the black Shiva.
but this is linked to another problem: now I can't get Lulu's solaris weapon because there's no save sphere unless you go into the chamber of the faith, so there's no way of getting back to the airship from there :/
edit: you're pretty much fucked if you want any real progress before you have to beat the dark aeons.
spoiler: without the hidden item from Macalania temple I can't get Anima, thus I can't progress in beating Belgmene's aeons and get Yuna's moon sigil, furthermore: by not getting to Anima I can't can reach the save sphere in Temple Baaj, thus I can't get Lulu's solaris weapon
might as well throw ~50h of progress away and continue with my save of Macalania temple..... and another weekend's gonna be "wasted" -_-