That is very impressive. So your device has only room for one single frame, so it can't double-buffer a frame? (I know that would cause more delay and/or jerkiness, but would not have any tearing)
Yes Hercules will be difficult. I've thought a bit about it in the past and came into conclusion that it can be done in frame-sync/line-conversion method by doubling pixels and tripling the lines into 1080p50 format.
Not all countries have TVs that support 1080p50, but we have them here.
But I like how your device works around it so that won't be a problem and works with computer monitors. They have less delay/lag than TVs, even when TVs are set to low latency game mode.