In case you are wondering what the Down Imaging software upgrade will do for you, I did this screen shot last week between snow storms and frozen lake thawings:

Wayne,

  That looks fantastic!  I can't wait to get back out with my SI!  The only water my boat has seen was a few minutes to get it winterized!  Judging by the weather, my next chance to try out down imaging will be on Stick Marsh on March 28th.

Got a question: Not withstanding what some reps may claim it is my undersatanding that the si works best at slower speeds, Does it operate like non-si sonars when at speed when the si is turned off?

Reo,

    The slower and straigher you travel the better the SI image.  Usually less than 5 MPH.  Due to the size and expense of the transducer it is placed higher on the transom to reduce the possibility of collision.  In these locations the transducer does not perform well when the boat is on plane.  It is recommended that you use a second non-SI transducer for depth while on plane.  You can connect the second transducer via a Y cable or a Tranducer switch.  I have the switch and use the second transducer that is epoxied into my boat.

Thank you, good info. I could also keep my current lowrance and just add the si. Any downfall with this besides for making sure there is room on the dash?

The Lowrance guys are thrilled the the Structure Scan.  I am not completely familiar with details of it.  The screen shots look great.  Finding a place to mount the display can be challenging.  The wider units don't fit into the smaller locations of most boats.  Most people use a RAM mount.  If it is on a RAM mount you can easily remove it from the boat so that it doesn't get stolen. 

Not what I meant, sorry. I meant I have an older (about 4 years old) lowrance on the boat now. It is fully functional. I was going to replace it with a 798 SI. To avoid the two xducer buy would there be any issue with just adding the hbird for low speed si work and keeping the lowrance too. Sorry for the confusion :-?

Running both shouldn't be a problem. 

reo, having two sonar units on the console with one being SI has been standard practice since Humminbird introduced the Side Imaging units. Even the Lowrance guys did it since Lowrance did not have that technology until mid 2009.

Thanks fellas

Hey all of you Side Scanning people.  Does that side scan work in really shallow water??  Say depths 2-3 ft? 

TommyBass, check some of the shallow SI images posted by Doug Vahrenberg on the Yahoo SI Group site.

Thanks Wayne... I didn't see that there was an extra page of those images!

TommyBass, PM sent