Mixing Avamar versions; ok to have a 7.2 source and a 7.3 destination?

I have (3) grids, two of which replicate bidirectionally; there is a third single node grid that replicates to one of the bidirectional ones.

Is it ok to upgrade the bidirectional multinode grids to 7.3, but keep the single node at 7.2?

I have a number of W2K3 clients that are no longer supported under 7.3 and I would like to "pile" all the W2K3 clients onto the single node (7.2) grid and continue with keeping current on the multimode grids.  Are there any ramifications for restores (even in a DR situation) as long as I have a 7.2 versioned grid available?

Thanks