I got the display board before I got the HV board, so I populated it and programmed it through the header I left for that purpose, and it works great.

The HV board was delayed because I kept messing up the order for the components, but I finally got it built last night. Unfortunately the performance is not what it should be - the transformer gets very hot, unlike the larger dev board (with the same components) I've been using so far. Ringing is very bad on it, and although I can snub it, that doesn't fix the over heating issue.

So, I've changed the layout to be much more like the dev board: I've been very careful about having no conductive elements unde the transformer, all of the active components are now on the same side of the board and are connected with copper pours rather than just tracks, there are no loops in the ground pour.

I've expedited an order from OSHPark - this board is so small, it is still ridiculously cheap, and fingers crossed that this will fix the issue with the transformer temperature.