Can I ask regardless of what backup solution you use:
1) Have you ever had backup jobs fail? If so what caused them to fail, and is it quite common for them to fail? Or a once a year type scenario?
2) What mechanisms do you have in place to identify a backup job that didnt complete successfully, and what can you do about a failed backup job? i.e. if it failed it failed, theres no much you can do about it?