Sony a9 vs Fujifilm XH2s for concerts

I can't decide which camera to upgrade to. I can find them both for relatively the same price and I was drawn to their stacked sensors for shooting events like concerts. I've been using the Fujifilm xt3 as a work horse for a while and have some lenses for Fuji already.

The a9 really caught my attention because it fell in my budget around 1500~, and it's full frame. I know that the xh2s came out more recently but I've heard that the a9 still does very well today.

What are your thoughts? Guidance and advice would be greatly appreciated :))