Replacing Lumi with IG88?

I'm currently having this team setup for arena: maxed Sid (lead), 6* Poe, maxed Lumi, 6* GS, 6* Poggle and I'm pretty secured in Top 10 daily. Unfortunately there's two other team in my server having the exact same build and I have 0 chance on beating them as they are lv 70, whereas myself at 68. Just wondering if I change things up by replacing IG88 with Lumi would help? I'm quite skeptical bout the idea as I've never battle without a healer in arena before.