170 cranks are a must on most of these newer long/low/slack type things. Plus they are a better fit for most S/M/L size people anyway. From my limited understanding of road fit, 175s only give you a good foot position if you are really tall, and that is usually with a steeper seat angle. Chuck in a slacker seat angle and you need an even shorter crank arm still to maintain the correct knee cap plumb line/pedal axle alignment.
That could all be wrong, I am mechanic not a bike fit specialist. Or a road rider really, but I know on my CX bike 170 feels much better, in the same way I much prefer steep seat angles.
Somewhere along the line 175 became standard for new mountain bikes, but I am pretty sure it’s wrong.
We have stock of medium Scouts, medium Patrols, and one large Smuggler. With a bit of a gap between last 2015 delivery and first 2016 we bought up what we could to bridge the gap. Selling pretty fast but still a few left.
Doing a fun enduro this weekend on my Smuggler, should be a good race.