I was pondering this before adding a .270 to my cabinet.
I have a stainless barrelled 243 and ended up going for a blued 270, the only reason being was that I found in the "gloaming" or on bright mornings, the stainless barrel really seems to stand out more and give a bit more "glint" off the barrel.
I know it's not a major issue but that was really the only deciding factor for me as a new blued/synth T3 was £674 and the stainless was only the price of a few boxes of ammo more at £780.
I'm sure if they are both looked after then it's really down to personal choice.
I liken it to fishing rods, I prefer a matt finish to my rod blanks as I always see varnished rods glinting in the sun from a good distance away when on the river and it always makes me wonder how much that could put a fish off??
Might sound like I'm talking p1sh but it's just a confidence thing...
rb