As long as the Top of Rack switch used meets the requirements of VxRail, there shouldn't be an issue.

More on the plug-in for vCenter 6.0 is here:

Cisco ACI Virtualization Guide, Release 2.0(1) and 2.0(2) - Cisco ACI vCenter Plugin [Cisco Application Policy Infrastr…

I have a customer looking to integrate VxRail 4.0.x running internal VCenter into an ACI environment. As part of this process, the APICs will be installing a new DVS into the VxRail VCenter and install new port groups. All hosts and VMs will have to be migrated into the new DVS. The original DVS created by VxRail manager during provisioning will be removed. Will this cause issues with VxRail manager, since it will no longer be able to see the original DVS and port groups?

The vswitch created by the ACI & VXRail does not go in hand.Once you have completed the vmm integration, the ACI will create a vswitch which cannot be used by Vxrail

The integration does not work well.

There is no real integration VxRail/ACI. The additional vSwitch will be created only on the additional NICs and you can look at SoleVe to see what traffics can be migrated to the new Port Groups. You can definitely migrate VM Traffic, the rest depend on the VxRail Version. Migrating completely to the ACI created vSwitch is unsupported and will brace future upgrades.

Is this information still up to date?  No vmm intergration with ACI?  It seems like most people have just trunked their vxrail environment to ACI in all cases I can find.