100 miniMADs is an option. Do you display the content on screens or do you need video mapping ? We did this 28 screens setup: https://www.youtube.com/watch?v=YqKo7WgSI88
Now in MadMapper you can use framebuffer mode to have 1080p30 if there's no video mapping involved (just fullscreen)
On PC, I can control 16 full HD screens at 60 Hz from one GPU with 4 Datapath FX4. I added another GPU, a matrox TripleHead and still get flent 60 FPS with MadMapper 4.0 beta: https://www.youtube.com/watch?v=jwUdfu5LsiU
However, going to more is challenging and we don't guarantee the results. Wen adding another TripleHead, I got 30 FPS, I still have to investigate where the bottleneck is.
It is possible to control MadMapper video playback from an OSC control broadcasted to all computers. Depending on the heaviness of the movie, you can get quite good synchro. We'll do some tests soon.