upgrading a cluster with Gen4 and Gen5 hardware to Gen6

Found some documentation on upgrading a Gen4 *or* Gen5 cluster to a Gen6, but nothing on a mixed cluster to Gen6 ...wondering if this can be done with SmartPools and Smartfail on nodes, as opposed to something like SyncIQ to a new cluster.  Details...

Current Cluster
6 x X200 (Gen4)
1 x X210 (Gen5)

Will be adding 4 x H500 with the goal of phasing out the above older hardware.  Ideally, on a high level, would like to add the 4 new nodes to the existing Cluster/SmartPool, let it re-balance and then smartfail the older nodes 1 by 1.  SmartPools is licensed.

Any input/experience is appreciated, thanks!