I dropped down to a 170 crank for my Rando/endurance bike build. The gearing is a good bit lower than the other rigs too and I find it very comfortable humming away with the smaller cranks. The BB is also lower so frankly a longer crank would be hazardous with pedal strike what with big flat pedals and heading off the tarmac..
My partner is about your height and has 165's on her Rando. Low gears like you too. Loves it.
As others have mentioned, Ive found age related knee damage is more niggly with larger cranks. Not sure of the mechanics regards to that.
I do still road race with longer cranks, but accept there will be a price to be paid. Endurance stuff though, when power output is dialled way back Im loving the shorter cranks.
This is my experience. I appreciate that a sample group of one is not good and that others might have different experiences - but:
In my experience the biomechanics are relatively simple. As the cartiledge in the knee wears up to the point where there isn't any and you're running on bone-bone interface the angle through which your knee can bend reduces dramatically. In my case before joint replacement I was down to 90°. I don't know what my knee angle was when I was young and spinning 175 cranks since I only learnt about this during physio after the op and with a replacement joint you're not supposed to go beyond 135° ('cos that's the design limit of the joint). What happens is that when the angle reduces eventually you can't bend the knee enough at the top of the stroke to go over the top. You get round this by pushing a bit with the other leg (at a not particularly efficient part of the stroke) giving pain in the bad joint and fatigue in the good one (and it often appears to affect one knee long before the other). Raising the saddle means that your good leg is less efficient and the bad leg, having an articulation that is stiffer than it should be, ,doesn't want to go round at the bottom of the stroke. If you can't get the bars up to balance the new saddle height your back can suffer as well! (I know all this because at the time I was piloting tandems in a club for visually handicapped and at the end I had the seatpost over the limit marks and the bars about 15-20cm too low - i stopped doing the tandemming!)
After the joint replacement I continued with 165 cranks and they were wonderful, 170's were just a bit too tight. After 3 years 170's have become more useable and now after 4 years, while I prefer the shorter cranks, if nothing else were available I could quite happily ride 170's (although not 175 mtb cranks though).
For the record I am 1m80 now but I've lost at least 5cms due to wear in the lumbar vertebrae. Don't ask the leg length, I haven't a clue but the height reduction is due to the back so the leg length won't have changed that much in the last half century.
