Yeah, I would see what other people are riding for the terrain you are going to be riding. "Smooth" and "gnarly" and even "XC" mean very different things to different people and varies a bit by location.
Also, the difference in feel between 150mm and 160mm travel by itself (all else equal) is pretty negligible. Spring rate/curve, damping settings, and fork stiffness will make more of a difference than 10mm travel.
That said, I rode everything from long smooth xc rides to big stuff in Moab on a 140mm fork for many many years (2005 RS Pike with some mods). I now do it all on a 160mm fork (2013 RS Lyrik), but in reality I have never seen the last 15mm travel, so I guess it is 145mm for all practical purposes. But it FEELS like a lot more travel, for better and for worse.
I would consider the whole bike rather than just the fork.