^ the processor in the xpro2 is very nice indeed and the handling is better and the focusing faster. It's a meaningful improvement. But whether it's worth the cash to you, only you can say...
It's the better, faster auto-focus that would motivate me to upgrade.
You notice it most with the newer lenses tbh, but it's massively better.
I've only got two lenses - the 35mm F1.4 and the 56mm F1.2, the Xpro-1 seems to have more issues with the latter, but with both I have to switch to manual focus in lower light conditions.
It's the better, faster auto-focus that would motivate me to upgrade.