Like it's actually possible (and it's already great to just have readable formated text and not a strange or xml file like with most of saving apps), but that would be perfect to have the ability to select all messages from a single discussion to export them all.
I just can't manually select more than 18.000 messages, but I don't want to lose them, and stock sms doesn't read sms from Titanium Backup saves (of Textra app and data).