A charge would discourage low balance users from voting, something that we should try to avoid. However I think creating a poll should incur some type of fee so we don't encourage poll spam. Maybe 500 GRC? And minimum balance of 25k to 100k GRC.
Whales could still get around most countermeasures by splitting their wallets. And there is no real need to alienate them anyways, they have a right to vote with their coins. I don't think punishing any whale is the answer. Whales have the most to lose if GRC goes downhill.
The magnitude idea is the most interesting IMO but could give a lot of power to pomegranate/pool operators.