Hi Mike,
Well, as you say, if you have an accident then the least of your problems is going to be a missing headrest ! The pillars are close to the driver but I've never really bothered too much about it myself, I just don't notice it once I'm in the car. But I do understand what you mean, a lot of modern cars here seem to have much wider screen pillars and I find them distracting.
So, will it make a difference ? I don't know. For me, my head just rests lightly on the padding so I'd say if you're the same then reducing it should make a difference. But will an inch or so be noticeable to you ? If so, go for it, it's your car and you're the driver after all.
Brian