Part of that training philosophy makes a lot of sense to me - if I haven't trained a horse to respond to my voice and body language, and I can't get whoa, go and turn with voice and body language, I agree, the horse isn't ready for a bit, and riding him in a bit isn't going to give me more control. I've wasted a lot of air trying to convince people that there's nothing magic about a piece of metal in a horse's mouth that makes him stop and turn; it's how the horse has been trained to respond to the piece of metal that does that.
However, my answer to people having hard hands and using the reins for balance is to teach them to ride more effectively, for example, correct their position and balance, and teach the sequence of aids, not to have them ride in a $110. rope hackamore.
Back to the OP, my experiences with hackamores are similiar to other posters. I prefer a bit; I like being able to "play" and work the bit in the horse's mouth, and I think a bit gives you more flexibility with your aids. But some horses, for whatever reasons, respond and go better in a hackamore. If I've run the gamut trying to find a bit that fits, is comfortable and works for an individual horse and haven't found anything that works, sure, I'll try a bosal or a hackamore. And if they work, I'll happily ride the horse in that.
However, I strongly disagree with the suggestion the a bit offers more "control"; that's an illusion. Control comes from training, not from equipment.
My two cents.