Thanks for your answer.
10GB for vmotion is really very fast. If you have an ESXi with 256 GB RAM, it's impressive how fast the vms are moved to another ESXi host.
I am testing a configuration with only 2 NICs with 10GB each at the moment and I built it as proposed here: vSphere networking configuration with 10 GbE | VMwaremine - Mine of knowledge about virtualization (szenario one).
I think this design makes sense and I have plenty of speed with vmotion, management and all the trunk ports. (vDS are not available because I don't have enterprise plus licenses)
Best regards
Roland