My son has a POS FS mountain bike that his dad bought him several years ago. Not only is it a crap bike, it is too small for him. I had him sized and they put him on a small Cannondale F7 disc. I'm really wanting to get him that bike for Christmas but I am wondering if the huge overall quality improvement would be enough to offset him going back to a hardtail after riding FS. Thoughts/opinions?