there is always MS Outlook… but I want to keep work and personal separate and like you want a nicer look than TB.
but give Postbox a look.
I have imported messages using “your” method (ie using ImportExport add-on) and it works perfect - no corrupted/lost/invalid emails.
This only confirms that eM Client import from TB wizard is “pants”.
I had a look at Postbox - there is too many free clients available to pay for one.
I am happy to solve problems myself and work on forums (instead of relying on support guys) in exchange for free version.