Monthly billing might fall through the cracks, IMO, so I think annual is still a good idea. (as someone else suggested) It would be nice to see it start from (and expire a year from..) the day you apply, not on a fixed schedule.
However, there may be software issues/challenges to look at. The membership software (IMIS) is set up a certain way, and PPFA is probably not the only group sharing it within PMA. Before something like that can be considered, someone will have review any software implications. I supported a very similar (trade organization) client, until a few years ago, which used the same software. Their organization did the same thing, with a fixed yearly renewal date.
Looking on the vendor's site, I see that it supports "Annual Billing: Used when all renewing customers have the same Begin and End dates. The Begin Date could vary for new customers who join later in the year, and their dues can be prorated for a partial term." and "Anniversary Billing: Used when the membership terms fluctuate; usually corresponds to each customer's Join Month or subscription Begin Month." However, while a change like this sounds easy - it could also mean a lot more work for the folks at the office. Everything would have to be done twelve times per year, instead of once per year. (billing, following up, email blasts, re-billing those who did not respond, mailing out materials, etc) So there are probably a lot of things to be considered, including the increased labor costs, for this to happen.
This would be a good topic for board discussion/consideration, IMO.
Mike