PhD Journey 2nd Year: Looking for perspective/focus
Would pursuit of this new track in any way compromise your chances of getting the PhD in a reasonable time? If no, then it must surely to be better to research something that excites you rather than plod on with something that does not.

If, however, your PhD is the key to your future career, then why risk it for the sake of pursuing an idea that you can safely pursue after you win your PhD.

I too am in the second year of a PhD but my future career does not depend on it. I feel free to pursue interesting ideas, and if that delays my PhD I am happy with that. 

So it all depends on your appetite for risk>