Heres some di shots from my humminbirds.there not of the same structure so its still not a good comparison,but its the best I can come up with.the dedicated di does way outperform the di/from si,but just like crappiepappy stated.even the cheapest units with a dedicated di with perform enough for most people. First picture is the 597,second picture is the 998,third picture is the 998,with the transducer rotated,then the last picture is from the onix