In my experience, it's a firmware 3.x vs firmware 5.x+ difference. All players with 5.x+ firmwares go to black screen for the screensaver if an roScreen is at the top of the stack.
My Channels: http://roku.permanence.com - Twitter: @TheEndlessDev
Instant Watch Browser (NetflixIWB), Aquarium Screensaver (AQUARIUM), Clever Clocks Screensaver (CLEVERCLOCKS), iTunes Podcasts (ITPC), My Channels (MYCHANNELS)