I sometimes make songs in triplets. I just set “highlight every x row” to 3 and compose this way. It’s IMO the most logical way of getting jazzy swing and… well… triplets 
.
The thing that bugs me is that if for example I work on two songs at the same time and one of them is in triplets while the second one is not, I have to go to config section every time I open one or another.
If I remember right, in Impulse Tracker the highlight settings were saved within the song. Maybe it would be possible to do it in Renoise?