I do have iTunes Match and, unlike you it seems, I know it doesn't backup lossless copies of audio files. My iTunes library also contains several videos, which iTunes Match does nothing with. The total is well over 500GB.
iPhoto collection (with only a few videos) is 500GB aloneiTunes library is well over 500GB (Apple lossless rips). Besides, why would I entrust personal data to Apple, when they hold the encryption keys? For much of the data I wish to replicate, I use BitTorrent Sync. BTSync isn't a recommended solution for iPhoto or iTunes, and I don't use it for that, but for other important files, it works great.