I have also not yet read the paper, but to your point about SSDs -- SSDs are definitely good for random reads, but for random writes, it seems like having an ap

I have also not yet read the paper, but to your point about SSDs -- SSDs are definitely good for random reads, but for random writes, it seems like having an append-only structure would help avoid write amplification. If you do a lot of small random writes to an SSD that will be slow and reduce the disk's life drastically. (That said, I'm no SSD expert, so I might be way off)