Replying to Sizing for K2 DOMAIN

So I'm looking at buying some K2 Domains but I've run into a bit of a problem.
The only sizes my boss can get from the supplier are 179 and 169. The problem is I don't know which size to choose.

I'm 5'10 and I ride 171 el rays. I was planning on getting the domains in 174 but obviously I can't.

As we all know K2 skis run large so a 179 would probably be around 180 to 181 and I feel like that would be way to much of a jump from 171.

BUT that also means that the 169 would be around the same size ski as I have know, but I'm worried that a ski around 171 would be too small once I start progressing more.

Sorry if this thread isn't worded very well.

tl;dr

If I'm 5'10 should I buy 179 K2 DOMAIN or 169?