We use R1Soft never had any problems with it. Off site backups are good due to the data being in a separate physical location if something really bad should happen, war, natural disaster or similar. Onsite is also good to use but only if the backup's are on a separate isolated server or your backup media (tapes, do people still use these ) are in a fire proof safe.
I have a storage cluster in RAID 10, and with Plesk I use the scheduled backup tool to make daily incremental backup. And for VPS, the SSD are in RAID 10, and I just make 2 snapshot per week. All the storage is offsite but it's more for the storage price, than for the security.
We use R1Soft Ofsite backups on daily bases for shared, reseller, VPS and dedicated.
We dont include R1Soft backup for unmanaged VPS/dedicated as it would just bring the price of it higher and instead leave it as an option for the customer.