Samsung quotes 148 MB/s per watt for the PM1643, for sequential transfers. Hard drive performance tops out around 270 MB/s and draws something less than ~9.5W, so the SSD is 3-5x more efficient for sequential transfers. For random IO, it's several orders of magnitude difference in performance and efficiency.
The most power-efficient consumer SSDs are an order of magnitude more efficient for sequential transfers than the Samsung PM1643. Eg: https://www.anandtech.com/bench/SSD18/2460
The most power-efficient consumer SSDs are an order of magnitude more efficient for sequential transfers than the Samsung PM1643. Eg: https://www.anandtech.com/bench/SSD18/2460