I also find edibles can be very hard on the digestive system. I've had canker sore type spots in my mouth, the sensation of battery acid eroding my stomach, slight to extreme nausea, and also had experiences with none of these unpleasant aspects.
It has always been homemade edibles causing this, and recently switching to dispensery products has largely eliminated all of these things. I strongly believe many of the negatives come from tainted bud, whether it's pesticides (the worst), fungus, mold, mildew, other bacteria or things we don't even know about.
That being said I find no matter what source of cannabis is ingested I agree with
@biohacker that it depletes vitamins and minerals, as I frequently feel physically weak when edibles are in my routine. This has been happening for years and is the same feeling as not eating for hours, and I've done enough trial and error to know it's the edibles causing this.
I think a homemade batch can be great, so long as the Cannabis used is clean. I will be testing this theory over the weekend for the first time.
I agree that low temp vaping is the best delivery method, no question, but at this point really couldn't see myself without edibles any more than I could see myself without a vaporizer. I find that when ingesting clean edible products (clean based on current industry standards, which are going to come a long way with legalization) I get enough positives to justify the negatives, but it takes a LOT of effort with diet, sleep and exercise to keep up with them.
Looking forward to lab tested pharmaceutical grade cannabis extracts designed for effective absorbtion in oral ingestion. Is that so much to ask?