You seem very pro soft plumbing lol. I do not have any links...just referencing my personal experience. I just feel safer with a glued PVC joint that cannot move. Regarding the cracks on hoses, it obviously depends on the material used. I have not had the soft tubing crack........just the stuff that is included with wet/dry filters (like your first picture on the right). I just don't see any positives to using soft over hard other than if it is needed based on location, where hard plumbing is not feasible. There has to be a reason you cannot use soft tubing to plumb a house right? Actually I have no idea if that is even true....just sounded good to support my argument