I do not own one but have vied a lot of pictures from them had read a lot
about them from people that own them on a hummingbird side imaging
site on facebook. They both put out great pictures. The helix is basicly
the old style of getting around on the system as far as settings and
functions. The solix is touch screen you can move around on it very
quickly . The solix does use a lot of battery power most people are
having to wire direct from unit to battery and use bigger wire.
also going to a size 31 battery if running other things off of it.
I bought my son a solix 12 mega for christmas and he loves it
just has not had time to use it a lot yet. here are some comparisons
of each one on the water helix vs solix https://www.youtube.com/watch?v=lIg6Hms7t3o
ALSO HELIX VS SOLIX 360https://www.youtube.com/watch?v=8mK6qFs8PKE