If I don’t buy the HD multimedia projector, will I lose any major functionality?

No. Aido without the HD multimedia projector is a joy to have around home as well. You can still use the head projector, home theatre system and music/movie streaming for entertainment. Aido will support gesture based interactive gaming, full mobility, the table top mode and the full range of Android apps.

You will miss out on the ability to project and watch movies with your friends, being able to read your newsfeed through the projector and other fun things with the projector.