Re: Preserve timestamp
FlashFXP can be configured to preserve the timestamp of files for both uploads and downloads.
This setting is located under the main menu > Options > File Transfer Rules
Then from the File Transfer Rules dialog Click on the Preserve file date tab to configure the options.
This can also be set per-site via the Site Manager.
The forum post you linked was a reference to a more complicated challenge of preserving a folder modified timestamp, this is more difficult because any change within the folder by any software or even the OS will automatically change the folder timestamp. It is very difficult to preserve the folder timestamp because simply viewing the folder content can in some cases cause the modified timestamp to change (i.e. when the OS generates thumbnails of media files).