Here's another problem with CharlieCard monthly passes: Currently, you can receive a discount on your car insurance by mailing 11 monthly passes to your insurance agent. With the CharlieCard, that won't be possible anymore.
When the CharlieCard was originally announced, it was touted as being a great thing for those who get their passes through employer programs (as I do), in that with payroll deduction, your CharlieCard will be automatically revalidated each month -- so no need to pick up a new pass. For subway and bus pass-holders, this sounds feasible. But on the commuter rail, unless a hand-held device or equivalent is introduced, it's not going to work.
I think this whole thing wasn't well through through by the MBTA.
Take the Diverging Route