Just a clarification, there are two advantages from refs integration: one is spaceless GFS as Joe noted, but also during transform there is a heavy reduction of I/O since now it's more metadata updates, and I believe this is what Peter was referring to. Forever incremental doesn't give any space reduction when using refs, but surely can benefit from I/O-less transform operations, the same used to run VEB backups. This said, final list of features is not available yet so I'll let to our product management to comment on refs compatibility.
EMEA Cloud Architect @ Veeam Software
Veeam VMCE #1