I have both (898/798) and certainly size makes a difference, if I had the $$ laying around I would love to have a 998 on the console. I do like the 798 up front, though it is a smaller screen, for the fact that it attaches via a quick release mount system. I remove the front one when trailering/transporting and the quick attach base/system is so simple and easy to use.
Sorry, no help here on the tranducer mount location for that boat.