SAM 2's key contribution is adding time-based segmentation to apply to videos. Even on images alone, the authors note [0] the image-based segmentation benchmark does exceed SAM 1 performance. There have been some weaknesses exposed in areas of SAM 2 vs SAM 1, like potentially medical images [1]. Efficient SAM trades SAM 1 accuracy for ~40x speedup. I suspect we will soon see Efficient SAM 2.