Meh, this distinction seems largely artificial to me. Modern fiat money is already created and destroyed through use of debt, and I hardly think that's what communists think of. And a strict "non-transferability" would beg the question of why would the "productive forces" (companies, cooperatives, or whatever) try to do produce things if they can't accumulate value based on consumers spending preferences (which is an issue which happened in the USSR).
Even worse : if vouchers don't fulfill the roles people want, you're still going to have a kind of informal money (gasoline, tobacco, seashells, etc... as said above), just with vouchers in parallel.
That being said, I never had much respect for Marx' political theories, so I would totally understand if you wanted to drop the point.