I reckon it's worth persevering with Thunderbird. I use it on all my machines, and rate it highly.
It does have the same annoying habit as Outlook, of burying your mail folders deep in the bowels of the file system. That can be changed, should you wish to do so.
It does keep the mail in a wide selection of separate folders, so is far less likely to lose the lot. I well remember the joys of Outlook.pst and its tendency to elope.