I own four of them and have shot a combination of factory and reloaded rounds without a problem for many years - like 30.
That said, there is probably a strain of truth in the bolt handle breaking off tale, kind of like "where there's smoke, there's fire."
I suspect that the people who encounter these issues are the ones who push a round to the absolute limits (past the limit, actually) so that you get a sticky bolt lift on ejection, that probably mixed with improper resizing so that you have a crush fit on closing. Neither scenario being a sound practice for a hunting round.
There is a smith that passes by this site that will tell you that he has had to redo 788 bolts, but he will also say that he does not know anything about the care and feeding of those broken rifles. Kind of like detached bolts on other makes and models.
Don't load like an idiot; if you need a faster round buy a different caliber, and you'll probably never have a 788 bolt handle issue.
788's are good functional hunting rifles who's price has been severely inflated in recent years. Maybe we ought to all start bemoaning the fragility of their bolts so that the demand and the price will drop. Let's all blow this concern way out of proportion......
If you need a functional rifle and the caliber and price suits you then buy it. Just don't reload like a moron and you'll probably never have a problem.