I guess it comes down to personal preference and what you value more, flying in PE and more comfort, or the cash in your back pocket after 6/7 hours in Y.
The recent sale has BOS at £630 up until March next year, but as June prices will have only just have started to come out, there is a good chance that the fares might still come down. What fare code are you being quoted for with the £980? Maybe the lower K fares have yet to be released.
I would be amazed if there isn't a sale between now and next June.
It all depends on how keen you are to secure seats on a particular flight. Personally I wouldn't dream of paying almost £1000 to fly PE to Boston. As Neil points out, sale fares make it much, much cheaper.
It is completely your call, but I would certainly hang on for a few months.