[RICO]

You make some compelling points to retain the May dates -

1) The tickets to see the Red Sox - wow, awesome.
2) The weather in Florida in May is, in my opinion, a tad nicer than September when the afternoon storms and associated humidity kick in.
3) Fall prices could easily (but may not be) significantly higher in September to New England due to all those tourists coming to see the wonderful foliage - although that can be quite finicky and can easily move weeks either side.
4) Decent price on your existing flight tickets.
5) Time to play with until balance is due.

But then you say the 'mask issue' could be a deal breaker. Only you can answer this one because no knows what the crystal ball will tell us. Are you unable to wear it due to claustrophobia or some other medical issue, or simply unwilling to wear for 7 hours on a flight? The rectangular white/blue surgical-type masks are not (in my opinion) too bad to wear for lengthy periods, especially in an air-conditioned plane with the vent above facing directly onto you. Remember, you can take them off to eat and drink on the plane.

Personally, I'd stick with the original plan but, this being a diverse board, you will likely get differing opinions. Ultimately, your decision matters. Good luck.