We planning to upgrade our current GroupWise 7.0.1 to GroupWise 8.0 (the backend engine) and the client side in summer.

On the BES side; we are running BES with GroupWise 6.5.7 happily working with the back-end running GroupWise 7.0.1.

Will there be any issue or problems with BES;
if we leave GroupWise 6.5.7 with BES alone and go ahead with upgrading GroupWise 7.0.1 to 8.0
or should we upgrade the GroupWise client on BES server from GroupWise 6.5.7 to GroupWise 7.0.1 for the least.