CC Findlay is the editor of F&SF, from whom I have collected three rejections so far. If you read the last resource in the list above, you’ll find F&SF uses a variety of form letters for stories not used, so you do get a touch of feedback about whether it wasn’t ready for prime time, your hook worked, there was some problem with the rest of the story or it was’t bad but somehow just didn’t make the cut.  (My analysis, not exactly what it says in his post.) I’ve gotten enough encouragement for some of my submissions that I think they’re worth revising and submitting elsewhere. I know if you can’t take rejection you shouldn’t be trying to publish, but you look for crumbs of acceptance wherever you can.