Welcome to Mint. I installed LMDE over Ubuntu maintaining my /home partition. On thing you may need to be aware of is that many of the applications in Debian Testing are behind Ubuntu versions. You may need to delete some .config files to get everything working properly (but it is possible with a few small adjustments). Some applications will notify you that the configurations are from newer version when you run them... On my other computer I ending up having to do a clean install and copying the data from backup (and this was with a Debian home folder). Be sure you back everything up first!