FWIW I think the model would work best if stability/regression and feature updates were kept separate as much as possible. That would require two updates a month though...
In "ideal land" for me... On the big day you could release two builds of Sonar...
(Build 1) With regression issues fixed from last months build.
(Build 2) Same as build 1 plus all the new fixes, enhancements and features.
User can choose between either...
With (Build 1) whilst it's a month older it will at least clear the annoying regression issues (new bugs).
With (Build 2) it's more whizz bang and up to date complete with new regression issues and bugs (but also more legacy bugs being fixed).
(Build 1) In fact could be released any time between releases.
It will be a toss up for the user to decide which build to take. Generally Build 1 would be more stable as regression bugs are fixed, however there would be occasions that Build 2 could be better as the legacy issues squashed could end up being more important.