Depends on what I'm brewing.
Made an English Mild a few weeks ago...let me just say that you are already mashing at the high end of the spectrum. Going over that is asking for trouble, so I'd rather miss low.
Saison? I typically do long mashes toward the bottom of the spectrum. If I'm over by a degree or two, I might not attenuate quite as much, but it's easy to just leave the mash tun open a bit and stir it some until the temp gets into the right range.