Ooh. I'm sure many will like this. And many, like me, will hate it. I have no intention of flying Y on any length leg. Now the calendar shows availability on every day of the week, whereas before it had maybe one day a week. I have to click into each day to see what's actually in it. Wish they'd put a checkbox on the search page to indicate whether or not to show mixed cabins. I know, I know, first-world problem and I'm spoiled.
I suppose it can be real advantageous in specific circumstances...