Replying to SPK out of park

So I tried on some Khaos SPK boots and they fit really well for me.  So I'm wondering if I buy them will they be alright in powder and cliffs and shit.  Because they guy at the shop said that they would hold up well for that kind of stuff.  I don't plan on having a super stiff bc ski and just charging the fuck out of steep powder.  I'd like to do BC jibbing, cliffs and stuff, not just all fast and steep and deep.  The guy in the shop said he used them when riding his fat skis in pow and that they were working very well.
So am I just dumb for thinking the SPK will be good anywhere but park?