In-Place hold is really not the same as a backup. The data itself is not in your possession but in the possession of Microsoft (not saying it is a bad thing but...) It means that MSFT still can have data loss (very unlikely but cloud providers have lost data before and it probably will happen again).
How much time is your in-place hold? What happens when they discover it 2 years after the fact (for example, when there is a lawsuit and you suddenly need the data).
How about 'restoring' the email to somewhere else (our explorer allows you to easily get it into .msg format, or .pst format for further processing).
Don't get me wrong. I believe in-place hold has a good reason to exist. But personally that is just another layer of defense for your data (legally, you are still responsible for the data, not MSFT) and VBO is another layer. Together you will make sure that you are much better secured against issues.
My 2 cents