The argument that an electric system is not feasible because it cannot be made 100% secure is null and self defeating if at the same time it is implicitly in support of a legacy paper system which is already exploited and cannot be made 100% secure. A better argument would be a cost-benefit analysis of both systems instead of defaulting to hypocritical defeatism. Security risks will always be a given.
I would say, though, that it would not be feasible given the current state of internet architecture. Internet infrastructure would need to become much more universally distributed and control would need to be relinquished by the current "internet gatekeepers" (i.e. Time Warner, Comcast etc.) as Aaron Swartz called them.
There is also the irony that in the US and elsewhere, the paper system is actively exploited and used as a means to make the electric system more insecure i.e. weakening/backdooring encryption.
With any new system, there will be technical challenges and unknowns that will be sorted out(ish) after trial and error as was the case with the Articles of Confederation which failed but then lead to the current longest lasting constitutional government today.