A couple of improvement ideas

[mixu]

Basically mostly I'd want a better ability to restart / rerun the task on the same folder:

• cache the results of the MD5 calculation since this takes a lot of time, particularly if you end up restarting the process
• run some of the compression tasks at the same time as the MD5 / do not block all progress until the MD5's complete
• warn if the disk would be too full at the end of the operation
• allow sorting files by size then name (to put all small files in one 7z output)