Just to clarify, in case you misread my contention, Highest recommended speed and maximum speed are two different things and I don't believe in maximum speed, especially as increased burning speed shortens lifespan.
My BenQ, for example, allows me to burn TY 8X media at 16X. This is not the rated speed at all. As well, stated above, quite a lot of media will deliver worse burns at slower than rated speeds. I don't really believe the original poster is getting 1X on his burns regardless of the settings, but I can get 1X on my Panasonic E50 and they are not as good as the rated speeds in any way. I have also seen plenty of 8X media that is worse at 4X, although some +R is a little better.
A general statement that slower burns are better is just not universally true.