We haven't really evaluated other options, we wouldn't be able to fairly compare this solution to anything else.

We are constantly looking just to make sure we are doing the right thing but haven't found anything that could hold a candle to Datto. Recently we have looked at Unitrends and StorageCraft but in my opinion neither comes close.

We evaluated Unitrends for a similar appliance approach. Cloudberry.  StorageGuardian and R1Soft by Continuum.  We are still looking for the best MSP friendly solution, that is more cost effective than Veeam.

Yes, several.