Suffice to say, Derpy's voice still sounded adorable, better than the edited version, even though I give credit to her replacement voice for effort. Still, one can't go wrong with Grey DeLisle voicing Derpy in the fan-work Epic Rage Time. If Tabitha St. Germain doesn't voice Derpy in Season 4, here's hoping Grey DeLisle will gladly take up the position, considering she loves the character.
Slightly off-topic, the best fan-voice I've ever heard for Derpy is the talent of Pierce Smoulder from the Doctor Whooves and Assistant audio drama series.