In many cases crooked old-time tunes depart from square by the addition or deletion of a boom-chuck. In as many or more cases they depart by addition or deletion of either a boom OR a chuck. Metrically that can always be handled with a mix of 4/4, 3/4 and half measures, but the accents frequently come out wrong.
Two features would facilitate accurate phrasing: (1) quarter measures - just a boom, no chuck. (2) the ability to replace a chuck with a boom (e.g. in 3/4, boom-chuck-boom boom-chuck-chuck).
The latest upgrade really does streamline the workflow. Deep thanks!