I do think its up to each individual to decide how to train his own dog and on reading your description of the sound on the collar, I wouldn‘t put it into the catagory of negative training. I would however have reservations about using one myself for several reasons. [this is not a criticism, just my personal opinion]
Firstly, I believe the best training is team based i.e. the dog and its owner build up a relationship and the training is a mutual cooperation. „Remote“ commands don‘t fit in, the dog should want to return to me because I have called him and, presumeably, its because he’s learned the advantage of doing so. The second disadvantage is that the dog has no point of orientation if the noise is coming from the collar, - are you north, south, east or west of him? How will he know which direction to find you? The third thing I would question is, you say want to recall him from 300 m? Again, I don‘t wish to sound critical but my dog is never that far away from me - he was trained at the outset with a long lead and he knows the acceptable distance, if he starts to stray further a „Too Far“ from me will turn him back.
He has, very occasionally caught a scent and gone shooting off but to be quite honest, if the whistle and recall doesn‘t interrupt him in the chase, a sounding collar won‘t either. I can quite honestly, hand on heart, say that he has never left my sight on a walk (and he’s off line 98% of the time) Where I live, there‘s a constant fear of hunters who will shoot any dog straying or hunting so teaching a reliable recall and knowing where my dog is at all times is essential. The collar you describe might sound like a good option but I don‘t think it would replace good training or help you deal with a dog with poor hearing. There are, unfortunately, very few quick fixes.