My guess is that it would depend somewhat upon technique. Not sure how hard some might press against the disc. Also, I'm not sure it would be enough for most people to notice (maybe even me?). In any case I have enough PSA to last me a while, so there won't be any changes in the near future. The formica cleans up pretty easily.
Believe me I am probably the worst pen maker on this site so take my words with a grain of salt. Many times I forget to post this is just my opinion as the escape clause. But just like each and everyone who posts ideas it is what has worked for them. Many times I try to explain my explanation and sometimes in may not come across well. But I do post alot here and this bothers many people here. But If I reach just ONE new person with an idea I think I did what I want to when I come here and partake as much as I do. Anything weather a method I use or technique is my way of doing things and if it helps someone then use it if not move on. It has been proven time and time again there is many many ways of doing the same things we do. Experimenting with the ways mentioned will help you find that way that works well for you. There is no right and wrong way, just different ways. I hope this clears up my thoughts.
You are right it is a matter of pressure but again my opinion and no it is not gospel as been pointed out above, What you want is a flat surface that is 90 degrees to the tube. Plain and simple. If you have a wobble or play in the tube as you hold it and put light pressure against hook and loop sandpaper on a disc, what is to say that surface is now flat and 90 degrees. If you press against a hard surface that is ensured. I use hook and loop for many of my hand held sanders and the ease of changing pads is great and that ever so slight round over is great to break the sharp edges of a box top or whatever. But remember it is a larger surface you are sanding then so bending the hooks and loops is tougher to do. But with a pen blank it is so much easier because you are concentrating in one small area. I also should note if using hook and loop pads to get the better grade because they do have a tendency to fly off a spinning tool if cheap quality. No you probably will not notice and as I also mentioned above some people may like that ever so slight round edge to break that sharp edge. Maybe it even helps with CA from not cracking on ends. I have no proof of this just throwing it out there.
This is all I am going to say about this and again MY OPINION ONLY!! Do whatever works for you. Good luck and happy turning.