Hello Cyberbenj,
There is no official recommendation as such. However, i have seen issues, if the customer's have more than 2000 VC's from single group. suggestion is to have two group's if you have 2000 VC's, it will also be easy for Airwave to push the config for 1000 devices once, compare to 2000. This would not affect much by just editing two group's VC config instead of one, but it will definetly save lot of delay in processing the request and resource consuming.