lowrance HDS units with ssi

Ok anyone out there have these? I currently have a lms 522 a great little unit but i want to upgrade and get side scannng imaging and the hd stuff.  I am looking at getting the HDS 8 model with the SSI box too a very pricy depth finder for sure!
  I read all kinds of reviews and people say the 5 and 7 model are prone to getting wet in the rain and not working correctly! didnt see any complaints aboput the 8 or 10 models they are drasticly different.
 opinions? is there anything compatable or better out there? is this the right one to buy? anyone that actualy has one speak up and tell me what you like or dont like about them.
  I am really very intrigued by the SSI features on these units cant wait to get out there and light up some water and get actual pictures of whats going on down there instead of some graph picture that needs interpretation!