I'd rate mine as a solid 8 .... but, that's comparing it to a b/w 2d unit, and that's not really a apples to apples comparison. That would be a Lowrance Elite 5 DSI vs a Lowrance Strata 128, and several other (older) models of Lowrance depthfinders. I'm giving the DI capabilities such a high mark, simply because I can see an "image" of what's beneath the transducer versus a pixel blob rendering that I would have to interpret.
To me, actually "seeing" that it is a tree, brushpile, stump, or whatever ... vs ... seeing a b/w or color "blob" of pixels, and basically having to guess what it is, makes Down Imaging more advantageous.
... cp