I'm finding it difficult to believe that this program is free, considering that other programs I've used in the past are so much more unwieldy and buggy. And I had to pay for those... Plus this is cross-platform, my biggest happy point.
I'm just investigating the program right now and haven't yet tried using it live, but the one thing I find lacking at this stage is a clear distinction between different verses (and choruses) in the preview and live sections.
I love how it automatically shows the breakdown of slides (since we often use quite large text on small sections of screen resulting in a verse being spread accorss 3-4 slides), but the difficulty I find with this is seeing where one verse ends and another begins.
You already have there the small margin with 'V4' or 'C1' to note it, but if these could be distinctly coloured - say verse 1 in green, verse 2 in orange etc..., it would make it very easy to see where to jump to when the singers start jumping around.
I realise that my colour suggestions are garish - perhaps muted versions might work to fit the colour scheme. But something along those lines would be wonderful.