although I am using VafW for backup of a physical DAG, I can confirm that until now, backup runs absolutely smoothly!
If you know Application Aware Image Processing from Backup & Replication: The options are the same.
If not, Exchange integration via VSS communication triggers Log truncation for distributed databases without any problems. Depending on your DAG configuration you need to back up only servers with unique DBs.
Recovery runs fine with Veeam Explorer for Exchange incl. granular item recovery.