here is my take on down imaging
my HB 597 CI HD DI is lower to middle end of the sonar pack . it has 455khz @16° and 200khz @25° for regular sonar and 455khz @75° and 800khz @45° in DI. yes you can use them at the same time with spit screen or split screen with the GPS. my sonar does not have side scan, wish it did.
DI is for structure, yes it does show fish but not as well as regular sonar but the cool thing with DI is with all the bait in the water lately it shows bait as individual smaller fish marks with larger marks (not bait fish) so your not just looking at a cloud like i see in 200KHZ regular sonar when the bait fish are packed up. yes it starts loosing the bottom at 250ft in salt.
DI kelp stringers look like kelp stringers, 80' to 120' you can see large bottom structure.
is it worth it for inshore? probably not for most anglers familiar with what their looking at but for me it helps me with what im seeing in regular sonar.
so for me, yes it's a cool toy.
it has some features like zoom and being able to record, take snap shots and watch/view on the computer when you get back. ok i know your next questions, wheres the records you have taken? i have some of the bay but don't have any in LJ. well i did but erased them. if you are interested in seeing what the sonar recordings at LJ looks like? i will try and take some and post them up.
heres a snaps shot and recording at SI
