I've been using the Pro Youngster for a couple of months now for my new 3½ year. He hadn't previously been given a hard feed, but took to the Pro Youngster without any problems.
PE was originally recommended to me by an equine podiatrist. I had been using the Pro Hoof Platinum for several years for my previous horse and more recently he was also on the Pro Joint Supreme. Both of those products were fantastic.
I'd highly recommend PE. Great products that work, with quality ingredients, nothing hidden.