It is always a good idea to not have read/writes going on while backing up. Having said that many businesses do it all the time. Good backup software such as Veeam or Acronis or even BackupAssist are designed to do backups during work. Some do it in real time, some every 15 minutes.
Of course, you say "main computer" so I am assuming it is not a server OS. I say this, because BackupAssist works directly with the OS backup application. While it will back up everything including SQL, there is a SQL add-on that not only allows you to back it up at say 6 am, but then use log files to back up every five minutes or so. These backups take about 2 to 3 seconds, maybe 8 seconds for the main database. These are designed to back up while working.
I guess my biggest question is why the need to back up at lunch. Is one-half day's work that important? If that info is that important ask her how much she thinks it is worth? Give it a dollar amount.
I say this, and I know it is a broken record, but likely the two of the most important pieces of information are your AC data and your billing data. Why not put it on a server that never gets used by a staff member, runs continuously, is designed to run applications and share files and allows you to use backup software that will do what you want.
And, using the main computer as a work computer is likely more problematic to AC than backups.
The other question is are you backing up just AC or II. If just AC, depending on the amount of data, it shouldn't take that long. I run mine manually, and it takes about three minutes.
Then there is software that just seems to know it doesn't want you backing it up while being used. You don't even have to be using it. With Medware, you can't back it up unless it is closed on every computer. Frustrating when users don't log out when they go home.
