I have tried something similar, I have 798 and also run a lowrance. If I were you, I would buy the 898. One of the nice things about the SI is that you will see great looking spots and want to mark those on your GPS. I wouldn’t want the hassle of switching my coordinates to the other unit all the time. On the other hand, one thing you might want to consider first is the screen view that you would use most often & look at some screen shots of it. There are a lot of options of screen views to see, and you can customize a few (on my 798 it is 3) buttons to quickly switch to a different view. One thing I don’t like is that I am unable to see all of the data (speed, for example) on all of the screens. I don’t know how the 898 works, but the 798 doesn’t show speed when I’m in a 3 way split (downscan, si, and sonar) for example. If someone can help me get this to work I’d be all ears!