I've seen mean Buckfast bees and viscous Buckfast bees.
I can only speak from experience with Buckfast , as that's all I've ever run. I've had as few as two and as many as ~75. Almost every year there has been an exceptionally hot hive, and almost every year there has been an incredibly gentle one (or two or three). Most are just "average" and by that I mean normally defensive of an intrusion into the hive.
I do believe I'm seeing a general trend towards aggressiveness. Last year 3 of my 7 were flat unpleasant to be around. One in particular would aggressively run folks off for days after working them, and "defend" the area 100' from the hive. 3 hives were "normal" and one was as gentle as can be ( I
could open it up with no smoke or protective gear).
Again - just me, and my experience with one "strain".