OK well Jemplode seems to be able to pull anything I want off of the central without a problem. I didn't realise that I needed to check the following boxes though to keep the tags so they'll work when I upload to the empeg:

Under Tools=>Options make sure:
1) Write ID3v2 Tags to Downloaded Files is turned ON
2) Preserve Existing Tag Frames is OFF
3) Remove ID3v1 Tags is ON


Currently it is a two step process and requires quite a few gigs on a HD since you have to download from the central to a HD then from the HD to the empeg. Drag and drop from the central to the empeg would be awesome.