Doing the force download trick only works if a new release is cued up and ready to go. However, if a new release is cued up, it will download almost instantly anyway. So normally it won't do any good. There are only a couple of situations where you can really force a new download,
One is when you get a brand new box which are usually not on the most current national release. The other time is during a CE download window. Of course then you're getting riskier software and you shouldn't unless you are willing participant in the CE program.
To tell what release you're on, you can either press and hold the info button or go to Menu -> Parental, Fav's & Setup -> System Setup and then press select on Info & Test. This will give you the original version and the past upgrade listing the release number and time stamp of when you got the download.
The current national release is 0x2af.