Both units will only share waypoints to the core units. Either unit is great. I run 2 helix's that are alsome, but I would buy the solix just for the customizable views.
A Helix is the current version of what the number series(core)was. Shares the same data---GPS/Sonar/Sensors/Accessories
The SOLIX will only share waypoints to Helix/core. Same as the ONIX.
The SOLIX is the new version of ONIX, they have the same operating software and same menu system.
All versions of the SOLIX are cross-touch.
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