I do not have experience with this particular saddle, but I can answer some of your questions. No, your saddle does not need breaking in. Your butt does experience some conditioning & toughening, but it is the large muscles that get tougher, not the bones, and most certainly not the sit bones. If you are okay up front, and you are not chafing to the point of rawness in the thighs, then you have solved the major issues that lead people to ditch a saddle & seek another. The one remaining issue of minimal padding is the easiest to solve -- try a short with a thicker chamois. I ride a hard saddle made with a carbon shell & not much in the way of padding. I wear well-padded shorts. I think for long rides this is the better solution. Too much padding on a saddle just squishes down & gives you too much contact area that can rub & irritate. Less is more. So try putting your padding in your shorts.

I am very interested in hearing how you fared on your 100 km ride as I am contemplating this same saddle. I've been riding the Arione for a couple of years now, which is fine in the back but bothers me in the front on a long ride. It seems to be a function of aging that I am more sensitive in front than when I was younger. It seems to be a lubrication issue, and the chamois creams only seem to be able to provide limited relief in that specific area. I haven't jumped out there to buy one yet because I haven't been able to decide between the Glider (same width, a little more padded), the Stratos & the Evolution (even less padding than the Stratos). Yours is right in the middle. Please write back with your impressions when you have the time.