I have the 14'er this last few months.
It's a powerful rod that will cast virtually anything you put through it, from skagit, to Scandi, to spey.
It is fast but not ultra fast, in other words it has feel.
My preferred lines on it are 38g AFS and 42g DTX heads, 10 or 11wt Rio scandi versi tip heads, 660 grain skagits, and 11wt 54' Gaelforce equaliser speyline with 5' polys. As I say, it will handle anything. Can't imagine what the 15'er might handle.
It's an easy rod to get on with, and one I can easily recommend.