Yes, closing speed does effect how hard it is to make a shot ie: you have less time to react and aim if you are closing from a 6 o'clock position on a buff that is doing 250 mph, and you are doing 500mph, this would general be the ideal speed to attack something, as it would be like you are only going 250mph towards a stationary object, but say you are coming in at 2:30 at the same speeds, you are now moving towards the bomber at 750mph, so you have 1/3 of the time to react as opposed to moving at a dead 6, does that make seance, I know what I'm talking about but I may not have worded it very well