If a trader is moving when he F1's, the reticule screws up and the person accelerates to a lot faster speed than cruise. Its pretty hard to destroy a trader when for about three of the 13 seconds left after waiting that you cant hit them. They don't just stop when they F1.
And yes, weapon groups is a really bad excuse. Time and again i forget mine especially in my bomber, but I do the groups while I fight. Its not that hard, and thats a poor excuse for F1ing. And as they say, of course you shoot someone when they reload. Thats the whole point of saving your bullets in a firefight.