It looks like Cabelas sells the 798 with a Navionics bundle that includes Navionics Gold and Hotmaps premium. This model does not include that bundle.
All 798's have dual sd card slots and can utilize Navionics and Lakemaster chips....check Navionics website for compatability to various versions of their mapping products.
A little caution, this sale model ($759) looks like the 2010 version of the 798 ci si. It would be worth calling them an asking if this unit has the ethernet port or not. If this is the 2010 model, it was on sale about a year ago for $699 when the new model was announced.....kind of surprised they still have this in stock.
The 798 that has ethernet would be the 798ci si hd.
Humminbird is heading quickly toward the ethernet communications for future expandability. If you think you might ever have a second unit you want to connect to, or want to take advantage of some of the new devices coming out for 2012 that use the ethernet hub, you may want to make sure it isn't the old model.