The Merckx is set up perfectly but the winter Bianchi is a different geometry, more sportive than racing snake, plus the seat post is stuck tight. I may invest in a new winter frame and just strip all the components off the existing one.
For saddles I've gone from a Fizik Alinate to a PRO Falcon. Getting it in the ideal position has been a challenge and going out to do a century without getting it dialled in was, literally, a pain in the arse.
Did a faster 100km yesterday which meant more time in the drops, which the shoulder complains about, and it felt far more comfortable. Riding on the tops, to alleviate pressure on the shoulder meant too much pressure on my sit bones and with the saddle not in the right position, that meant trouble.