hey,
it looks like your bithopper configuration lacks the mine_address for rfcpool.
just look in bithoppers pools.py if all pools have a valid mine_address
I can run your mod only after I commented (i.e. disabled) BTCPool24, bmunion, btcworld, nofeemining and poolmunity in user.cfg. All this pools have a valid mine_adress in pools.cfg. I have about 0.3% of rejected shares with your mod and this is excellent (tested about 1000 shares)! But your mod is not perfect: idle states after every share:
http://img12.imageshack.us/img12/289/clipboardimage8.png