Appcheck, this and similar saves a copy of the file when it is deleted, correct?
Short answer->AppCheck->free only backs up most recent few files on each drive in case some files are encrypted before AppCheck blocks a ransomware. Long answer below.
AppCheck pay does backup all files and it protects the MBR too. I have been looking at the activity of 360 DP, and it's unusual. As
@roger_m noted documents saved will be backed up by 360 DP. This includes to remote drives as I have just noted playing with saving documents. It just backed up a pic I saved to the D drive. However existing documents copied and pasted or moved from one location to another will not be backed up. Has to be an actual save event for the file to be added to the backup folder.
One other strange thing about 360 DP is that it is saving files from Program Files and from AppData in user space. I set it to save .txt and pic files so it's grabbing logs that get updated in prog areas and appdata and then also even pics in the Google Chrome cache. That's kind of messy honestly and as far as I can tell there isn't a way to define what is saved in the backup folder.
For now I just have 360 on here to study it for awhile. Hopefully Qihoo will refine it some. It has potential, but I feel it needs work.