You would pay based on a seven day hopper.
Disney sells tickets to the brokers at a discounted price and then does not care what price the brokers sell them at. Of course, Disney's retail price for a seven day hopper is only $2.13 (including tax) higher than for a six day hopper.
If you do any sort of upgrade to any MYW ticket where Disney's selling price was less than the current gate price, Disney will absorb the difference (including tax) between what Disney originally sold the ticket for and the current gate price. So you would only pay the difference between the current gate price before the upgrade and after the upgrade.
Note that the fee for a no expire is based on the total number of days available on the ticket, whether thay have been used or not.