I think no quicksaves would be better, as it is easy to say "Don't use them" but I know from experience that some people who would prefer not to quick save do so compulsively if they know they are available to them. I remember when playing SCCT, for example, that the first time I went through I would quick save so often that some times I caught myself doing it after walking through a corridor that didn't even have guards in it, after having saved just before the same corridor.
It has been proven in games like Rainbow Six that no quicksaves works. The problem comes when the missions get longer. As has been said, having to restart a mission you have been working at for an hour over and over again isn't a lot of fun. Rainbow Six worked because the missions were short. If the missions are short like in Raven Shield, for example, I think no quicksaves would be ideal. If not, then I still think there should be no quicksaves, but rather a checkpoint system that saves at predefined areas or after objectives, perhaps. Not completely realistic, but it isn't really much less realistic than restarting a mission. The problem with quick saves is that you don't have to be that careful, as you know if you unexpectedly come across an enemy you can just restart where you were 10 seconds ago.