Looking to do a similar setup during the off season. I have everything but the 1199. I'm debating on moving my 898 up front or just leaving my 858. I've been seeing where guys are using their SI units as dedicated DI units with good results. Then I could use the 2d out of the Terrova and along with a DI transducer to the 898. I don't really need SI up front but would like 2D and SI.