Really good and useful request.
Regarding accidental data loss: Checkvist Pro account gives you up to 10 daily backups of all your lists. Not the same, but may help in some cases.Mikhael Belanger commented
Having a history of modifications on each task would be incredible. 3 votes for that one!
217 votesAdminsashika (Admin, Checkvist) responded
Dear Adrian, thanks for giving your vote to this issue! We’ll try hard to keep the user interface simple – promise!