I would use whatever works for your dog. If she's highly motivated to work for praise, terrific, but most dogs need more than that. Toys are great, but it can be difficult to get in as many repetitions with a toy compared to food.
Not to take away from what you are saying, I do agree with it. But I love
the idea of a praise-only class. From my experience, too many trainers drill in your mind that food should be used to shape behaviors, and it does becomes the focus of a class, if you run out of food in a class then good luck, not to mention a better treat in someone else's hand is a big distraction. I can't count how many times it's happened to me, though I am working through sparse treating in that setting.
The Monks of New Skete have a wonderful approach for training, and I base a lot of what I do from their lectures and literature. You need to be truly sincere in praise, be extremely positive, really keep training short, max of twice a day, and always always end on the best effort. It honestly does build a better relationship and better behavior, as it requires much more effort on both sides of the party to keep interested and focused, and certainly does carry through to every other situation. It does help that they are monks and spend 100% of their time with their dogs. But the truth is, many of us do not have time for that bond, and we must use other motivators to train. Because of this, I don't think it is the dog that need more than praise, it is the handler that needs more than that to train.
ETA: I began my training praise only, to shape sit and down was very tough. I ended up having to physically shape the behavior once he learned what it actually meant and would protest it. I don't know if that is recommended, it now seems foolish of me to do it, but that's what Monks had suggested and those were the resources that I had. Of course, they are masters, and I am not even a novice, so taking that advice at face value was probably a mistake.