Depth finder

Don't know about the Lowrance but I have the Helix 7 and I have no complaints thus far.  
 
The 9 will give you more options than the 7, such as, building your own maps and of course the bigger screen.  Kinda, sort of, whished I had that map thingy capability if it does what it suppose to, but for now, I can record then plot on my 'puter any routes and/or waypoints.  
 
Side imaging and down imaging is a real asset once you learn (I still am) to use it.  Learning/practicing with all the different features gives ya sumthin to do when the fish ain't bitin.  
 
Good luck with your choice.