Dual PSU On XYYZ Router

I'm finalizing my control panel wiring. Full disclosure, when I have time to think, I can over think it.

So currently I have one PSU powering the two Y motors and one powering the X and Z motors.

There is no need to split the Y axis up across the two supplies is there? Maybe balance the load a little across the two PSU?

You'll be fine. I only use 1 PSU for all 4 motors. (Assuming correctly sized PSU's)

There may be a trade-off between load balancing and fault behaviour.
With your current arrangement, if the Y PSU stops then both motors stop.
This is probably a good thing.