The mei2archive tap updates any recordings you make with the extended programme descriptions present in a MyStuff.mei file. When finding the information to use it makes allowances for the recordings being padded, so lessing the chances of you ending up with the information from the previous programme.
You can still get the benefits of improved handling of padded recordings without a MyStuff.mei file, in which case it will use the internal Topfield EPG.
Topfield use a number of different file formats for recordings and mei2archive only supports the formats used by the TF5800 and TF5000 models.
You should normally download the release version. Test versions (when present) are just that and so please only download them when instructed. Please post any feedback on the TAPs forum on Toppy.org.uk.