Well the real selling point for me with people was that they would come in, swap the tape with a new one, and take that tape home. There was no auditing of what was being backed up, the success/failure of the job, etc. This was setup by another consultant long before me and never really addressed.
First off, I use Acronis True Image Enterprise Server for Server backups. It is a little on the pricey side from what I remember, but not entirely sure you would need to switch software packages if they already have a viable solution in place. In the environment I do, I perform FULL backups nightly, mostly because space isn't an issue (less than 3GB per backup), and when restores occur they need to be fast. I personally prefer not to have to deal with loading a full backup and then subsequent incrementals. However, I do have a client with 15GB nightly backups so I do things differently there. Another thing I like about Acronis, and I'm sure others have this as well, is I can send an e-mail to myself (and to my client, they like to be in the loop), with a summary of the backup job. It lists what was backed up, and the success or any failure. This gives me the ability to keep an eye on things without any effort, just check the e-mail once a day.
Once that is complete, I use WS_FTP Pro to transfer to the FTP site. WS_FTP goes right to the directory that I setup for this client, and the backups are named MONDAY, TUESDAY, WEDNESDAY, etc. As a result, once a week on either Saturday or Sunday, I transfer them all to a manually created, archived date folder. These folders are named such as WE 09-09-2007 (tomorrow's backup set). I keep a 30 day history, so each week when I create a new folder I delete the oldest. I have never had to go back that far, but again, it's a comfort item for them. With tapes they could go as far back as the tapes they had, with my service they can go back as far as 30 days (may actually have a client who wants a 90 day history as they are a CPA).
So, at this point, they have a 5 day history on site for emergency backups, and 30 days with me. Obviously if it's outside of the 5 day history I need to transfer files back to their location as needed.
Works really well, but keep in mind you should check with his ISP on the business side on their limitations to upstream bandwidth per month. Not very common, but good to know ahead of time instead of going into the office one morning and not having service because they killed your connection.
Not a lot too it really - if you have any other questions feel free to post
Good luck!