But keep in mind that delays are considerably more likely -- first because you're connecting at all, second because you're connecting through SFO, and third because you're connecting through SFO on a short flight (which will get targeted by any flow control). If you're not concerned about the additional travel time, however, then you may not care about potential delays either.

P.S. The superior frequencies at SFO are entirely due to UA's suffocating presence here. I would trade the situation at LAX, with five robust domestic competitors, for the situation at SFO (one, soon to be two, domestic choices) in a heartbeat, even if it meant fewer frequencies on a specific airline between SFO and BOS.