IMO... bark collars are just another training bandaid. Throw them in there with prongs, chokers, and anything else that controls a dog using pain/fear/avoidance. In general, they are a cop-out, and not solving any real issues. In fact, they create issues. I would much rather have a barking dog (and do no training) than have a barking dog who becomes fear-aggressive because of all of the negative associations that a bark collar can cause.

I would discuss it with your neighbor. Ask her if she has ever taught her Beagle a "quiet" command, a solid "come", "leave it", etc. Encourage her to get into Obedience classes with a local Obedience group or a certified behaviorist. Beagles definitely are vocal, and they need to be taught when enough is enough. Yelling at him to shut up isn't going to cut it, either. Nothing, no spraying/beeping/shocking collar, is a substitute for being present and training your dog. Beagles are also huge foodies, so using lots and lots of treats, good timing, and positive reinforcement for being quiet could probably quiet him down fairly easily. Training is not an instant fix and it requires more effort than pushing a remote (if even that), but it won't create a fearful, freaked out dog who is much more likely to bite first and bark later.