Just to share something related, I recently ordered the Aarn "X Strap" sternum strap replacement that is designed to fit any rucksack. BTW, the US web site is very convenient.
My 38 Kg Osprey Kestrel S/M (new this year, replacing a five-Camino 48 Kg Kestrel M/L) has a sternum strap that rides rather high on my somewhat prodigious torso. So, I thought, hmmm, this looks promising. I will give it a whirl... I do like evaluating new gear I come across...
Well, I fitted it as instructed and made some short test walks with my loaded rucksack, at 12 Kg. I am getting ready to leave a week from today. I much prefer walking the first few miles locally, so I can sort out any load or fitment issues without discomfort or drama. Things are much easier to repair, replace or adjust at home than once on Camino.
My observations are:
1. Having 'moobs' (sort of - they want to be muscles...honest they do!) the 'X' strap feature highlights this anatomical irregularity and looks sort of like a bra harness. Looking in the mirror and, once I stopped laughing at myself, I recalled that it looked akin to those empire-waisted shroud-like gowns that women wore way, back in the day (ancient Greek and Rome IIRC), also with a 'X' fitting chest strap...they accentuate the breasts, or so one imagines...NO THANK YOU! While it might be acceptable for some out there, it is NOT the look I am going for.
2. As if #1 were not enough, the 'feel' of the 'X strap' is different and it does not relieve the friction or strap pressure over the front of my shoulders as much as I thought it might.
I allow that folks with less of a chest and gut out-front will have a wholly different experience. And women, well...being shaped differently, will also have a different perspective. However, my chest shape is more akin to a classic wooden barrel....seriously! It is just the odd parts I was born with...
So, I returned to the basic sternum strap that came with the rucksack. If it continues to chafe, I can fashion a pad from a small microfiber towel... I am clever too...
Hope this helps.