when download complete move to folder “eg: completed downloads”
What about your seeding time?
i don’t think this is a problem auto resume upload after moving ^^
That’s certainly true. µtorrent has had this option for years, to move completed downloads to another pathname, and simply seeds it from the new location.
This is a single destination directory, you can’t elect to have it move some torrents here and some there, or to move some but not others. It’s still a very useful feature.
“Ή τάν ή επί τάς”
You would have made a fine Spartan soldier. 
At least as far as talking goes.
I’d actually like to see this feature implemented in the reverse which I think would be an easier solution to the problem.
I have a dedicated download drive (SSD) and many other storage drives (HDD). Currently I download all torrents to my download drive and have to manually move them to the storage drives. I’ll usually try and wait a week or until share ratio goes 4to1 but admittedly some tasks never get to that stage and I can’t use the LT Seed feature once manually moved.
What if you enabled a “Use dedicated download path” option in the BitComet options somewhere, which would download all tasks to that location (ignoring tags and the save path in the task properties) until completed, then moves the files to the originally planned save path and begins uploading and LT Seeding from there.
Perhaps to avoid confusion (although only experienced users would use this I imagine) when using this feature, a note or icon can appear near the task save path in the task properties window to notify you that the files aren’t there yet, but are located in the downloads area.