Setting
As well, if there is email that you (general you) possess that is world ending should it be lost, keeping it only in one location is not the safest course.
I should also note, that if you have an email that holds something super duper important. Why the smurf didn't you save it as a file and/or print it out?
The point of using gmail (and POP-moving any other accounts like Hotmail to it) is to centralize your receipt and management of all emails such that you are not tied to any ISP and have a reasonobly robust mail server that can be accessed via web, IMAP or mobile client reliably with zero issues when migrating.
While it is very reliable for storage, it is not a bank vault. it is not a safe. It is not suitable as a repository for critical information.
If it is critical, back it up yourself by saving it to a network drive or other removable media. I don't store ANYTHING that I absolutely can't lose on my computer.