but their page seems down now for some reason
Still up for me. When did you switch to i0.digbtc.net? If 9 coins were all you got from BTCG, then I would assume the rest of your 81 coins at the time you posted about having 90 coints, were all from i0digbtc?
I think that maybe if you had stuck to btcg, you would had came out ahead. I had pretty much zero coin for the first few difficulties but that was pretty much expected. Once it took more than 2~3 shares per block, my coin rate went up tremendously. Due to the sheer amount of hashing power BTCG have, it would also had been able to void/orphan blocks from other pools as well simply by racing ahead with a longer blockchain.