Hey Andrew,
GDataCopier is still under development, unfortunately it's mostly done in the spare time I have (with little bits of sponsored development) which I haven't had much of this year.
3.x is a complete rewrite of this utility, OAuth 2 implementation details were a little sketchy when I was working on it earlier this year, that slowed me down a little as well.
Might get to this over the coming months when I have a little more time available.
Please hang around on the list so we can keep you posted.
Are there any features in particular you are interested in?