I've not ridden the 171 AWD, but my feeling is that if you are comfortable with hardboots and plates in all conditions, and you plan to ride hardboots in the backcountry, the 171 AWD is the perfect board. If you are going to ride softies, the normal "Backcountry Splitboard" is the right choice.
My only gripe would be that the 171 would be long-ish for lighter riders in steep, hardpack terrain like spring mornings. I'd like to see Prior offer the 167 AWD shape in a split as well. However, hardboots + splitboards is combining two niches into one ultra-niche. There have got to be at least a *dozen* backcountry hardbooters worldwide that need something shorter than 171 right? That's a huge market segment... :-)