Nice work.
Some years back I was involved in a flashing wall using florescent tubes. (they had 11 columns and 3 rows...but thats another story)
We tried all sorts of methods to get a resonable rate of flash.
In the end we used Phillips?? Dimmable ballasts, and simply shorted out the 10v DC control, which made the lamp drop to about 3%.
Worked really well, and saves on switching mains.
Cheers
Mark