For the US2 in the trolling motor, that would be a non-MEGA unit SOLIX or Helix in the CHIRP version.
MEGA stands for MEGAHERTZ or 1.2 MKZ Imaging. They have 455 and 800 kHz Imaging also like your 1199.
The MEGA units have a dedicated Down Imaging crystal in the transducer so you get true DI and not composite DI like you do with the 1199.
If you want full data sharing, you would need a Helix with a Helix or SOLIX with a SOLIX.
Same as you can share all sonar technologies between the 1199 and 1159 sonar version.
The SOLIX is a little more "sofisticated" with positive and negative circuits to each transducer sensor (slightly better images). The Helix shares a common negative with all the transducer sensors--just a positive to each separate sensor.
Operational wise, the Helix has adjustable view panel sizes for dual views but no custom views. The SOLIX can have customized views up to 4 panels but the sizes are not adjustable.
The SOLIX has a somewhat more complicated menu system and touch screen. No Helix has a touch screen.
The Helix has the same menu system as the 1199 with more settings. That would be the shortest learning curve between units.
The MEGA SI transducer for both models is the same size with the same mount, just the cable and plugs are different so they are not interchangeable.
Product linewise, the Helix replaced the number series units and the SOLIX replaced the ONIX.
Edited by Wayne P. (05/25/17 06:11 PM)
Humminbird Helix 12 CHIRP SI, 1198c SI, 1198c SI, ONIX 10 SI NT, Helix 7 CHIRP SI GPS G2, SOLIX 12 SI, 360, RC-1