Hello,
The optimum way of routing management traffic and vMotion traffic really depends on your environment along with the available resources. The current set up is fine if you don't want to or can't use the other two available nics but I would implement some network I/O control since vMotion can saturate a network quickly. Personally, If I had two nics available with available switch ports I would offload the management to dedicated, redundant nics. You can all ways reclaim the two nics if you need them, like adding a third nic to the production VM VLANs or replacing a bad nic.
Best Regards,
B.