There is no specific limit per vfiler.. The 6080 limits for the entire controller are in effect and the total number of connections are based on the total of all vfilers. The 6080 can handle 96k user connections and 384k share connections and that can be split across the entire controller regardless of vfilers.
The default number of vfilers is 11, but you can increase to 65 (reboot needed). Each vfiler reserves about 400k of ram, so using vfilers (even to the max) won't be noticeable to performance.
So, it makes sense to create source vfilers then you can vfiler dr and have all your cifs shares updated on the target (since the vfiler has its own /etc in the replication).