Avamar SQL Agent running against live SQL Server databases
Please ask them and also, as max pointed out, test whether such tool can provide point in time recovery. Test various scenarios and see if it matches your RPO and RTO. I am sure its not free of cost only go if it REALLY provides some thing more than what native SQL Server Tsql backup provides. I have not found any tool more reliable than TSQL built in code for backup.

Ask them,if possible, to do a POC (proof of concept) and show you how it would be better than native TSQL backup. You have to let them know that there is no point in choosing any thing blindly if it does same work as a tool which you have free( inbuilt). You can professionally ask them above questions. Plus if you use such tool you might need to hire a person who is expert in this tool so might be some more extra cost.

Think all pros an cons and then move