i see now issues with that, host HBAs will auto-negotiate up. Windows/Linux running PowerPath ? No HPUX/AIX ?
I've a question regarding the SAN Fabric migration before going into the question I will mention a few words of our current environment.  We are having two Connectrix ED140M(Mc data) switches first one represents Fabric A and the other Fabric B, we want to migrate the same to two Cisco MDS 9506 switches. In MC data the ports are 2Gbps where as the MDS are 8Gbps.  We are hoping to do the migration without any down time so it is one switch at a time. So once migrated at a point of time one leg will be on 2Gbps switch and the other on 8Gbps.  Does this cause any issue with host connectivity to storage? The hosts run windows, linux and esxi os on them. 
Connectrix ED140M(Mc data) to Cisco MDS 9506 Migration