Try using filezilla with MIUI file explorer guys.. Using both together rocks! Filezilla allows resume of transfer from your last file when phone gets disconnected from the network.
For example, i'm backing up everything on my SD card which is total 3.3gb it would take several hours to transfer everything. If using USB or normal drag and drop with browser, everytime i need to go out of the house for awhile i need to stop transfer and start all over again.
With filezilla i just stop the service from MIUI file explorer, filezilla will try to reconnect to my phone but i just leave it.. Go out of the house for awhile come back home connect phone to wifi, start the MIUI file explorer PC sync and Filezilla will continue the transfer... Some files might fail when u disconnect from wifi while transfering, but Filezilla shows u which files failed and u can reupload them.
You can also use it to do incremental backup of your whole SD card, Filezilla allows overwrite of newer files base on timestamp.. There are alot of other features too.. Try it, it's opensource..
http://filezilla-project.org/