Is there anything new on this topic? I just wrote something out for a client in 3/4 time and now he wants it diminuted to 12/8 (4 bars > 1 bar). For Dorico, with its awareness of real note length (e.g. for tied notes) and powerful meter-changing-features, this should be really simple to implement… I really could use these rhythmic augmentation and diminution now. If you know any workarounds, these are welcome now, too (at the moment, I’d just try to export everything via MusicXML to Finale and reimport it, which will kill any layout refinements I made, I suppose).
And how about even other factors like 1.5 (converting triplets to three singles, like 4/4 with many triplets to 12/8)? This will be useful, too, and again, I don’t know which other notation software should be able to do this easier than Dorico.
Oh, and I did not find the other posts MarcLarcher mentioned (searched for augmentation, diminution, half rhythmic and some others)… so I’ll just add these keywords to this thread.