I have 165s on my old 80s trek road bike. I like them - I only feel they hurt climbing when I sit and spin. For standing and banging up a hill they are fine, maybe even smoother than the 170s on my other bikes.

As you'd expect they are nice and smooth sitting and spinning in an easy gear over flat ground.

I recently used an old three speed with 140mm cranks for commuting - they felt weird at first but I got used to them quickly. They did suck rather badly for my one daily seated climb (Queensboro Bridge, LI side), but other wise they were fine.....one funny thing; after a few weeks of commuting on the 140s my 170s on my other bikes (used on the weekends) felt monstrously long and uncomfortable to the point of mild pain!

Of course now that I ditched the three speed and use only 165-170s I am fine with them. 5mm will make a difference but unless you are a competitive racer I doubt a few mm will hurt you too much either way. (30mm is another story!! )