So as a "summer experiment", my synagogue decided to change around the order of Shabbat services a bit. From this weekend through the shabbat after labor day, or so the plan goes, we will start morning services a half hour later (9:30 rather than 9:00), skip the sermon, move musaf to be with mincha, and hopefully finish earlier than our traditional 12:00.
It's supposedly okay to move musaf to mincha-time, but no one seemed quite sure of how the details work. So our rabbi asked Joel Roth how it's done. After receiving an answer, our rabbi then went on his previously-scheduled vacation.
So this morning, in the first day of the experiment, we skipped just the musaf amidah and the chatzi kaddish before it, going straight from "etz chayim hee" to full kaddish, ein keloheinu, etc. Then, in the afternoon, we started with some random non-Ashrei psalm (we chose 93), then chatzi kaddish, musaf amidah, full kaddish, aleinu, mourner's kaddish, and then ashrei and the rest of the shabbat mincha service as normal.
I was sort of surprised that it turns out musaf is suppposed to go before mincha even in this configuration, rather than after. But I trust the source, so I trust that we got that one right. There are only 3 details that surprised me: I was surprised we did the "titkabal" line of the full kaddish after the morning torah service, given that I think that's only supposed to be said right after an amidah, and is omitted the other times you have an "extra" full kaddish (such as ma'ariv for purim or simchat torah). And I was surprised that we had an extra aleinu and mourner's kaddish after musaf. I would have expected that we'd just go straight into the mincha torah service without "ending" musaf in that way, just like you go straight from shacharit to the torah service on a typical shabbat morning (though we have the extra break here of ashrei, uva letzion, and chatzi kaddish); I'd expect only the one aleinu-and-mourner's-kaddish set at the end of mincha.
Oh, and how did the experiment go? Well, we ended at 11:40, though it took a quick torah reading while our usual ba'al koreh is on vacation to make it there. In future weeks, when he's back or when there's a double parsha or when someone (either the rabbi when he's back too or if a lay person is interested) decides to give a short devar torah in lieu of a sermon, we'll be hard pressed to finish as quickly. And a lot of people were complaining about missing musaf. But I didn't hear anyone complain about services starting later. And there were a LOT more people there for the shacharit amidah than there ever usually are, which was part of the point of the experiment. So I'd call it a qualified success so far.