I am thinking of upgrading my humminbird 9 gn1 si. I am debating between the helix 12 mega si and the solix 12 mega si. What is the difference between them other than touchscreen?

Very different menu systems.

The Helix has adjustable view sizes on dual views but not customizable views.
The SOLIX has customizable views that are not size adjustable.

The SOLIX will share mapping and the Helix will not.
The SOLIX will share Heading from a heading sensor/GPS antenna separate from GPS, the Helix will not.

Wayne is the di, si and 2d equally as good?

It's about the same with a slight edge to the SOLIX since each transducer element has its own positive and negative circuit. The Helix shares a common negative.
14 pin plug vs 7 pin plug.
You may not notice any difference.

so would you suggest upgrading from gen1 helix 9 si with hd transducer. i have not been very happy with the si on mine. i paid and went to an technology class with captain Craig here of TFF. He did help the 2d and di some. After a few months attempting to get more use to the new settings. I went to bass pro here in Garland, there is an old man there that i had many good suggestions to try him. I again think he helped but i get poor si images from alot of the pictures i seen on here. I also have leveled the transducer using the coin method, that helped. I very rarely see any type of tree type structure. i am thinking of upgrading to the helix 12 si. i use a pontoon so i will have to get an wye cable because my motor blocks partially to the left.

The Helix 9 has the lowest pixel density display of all the Helix units.
If you upgraded to the HDSI transducer from the standard Compact SI transducer, that is as good as you are going to get with that unit.

The first generation Helix 12 CHIRP SI GPS comes with the standard HDSI transducer.

Yes with a pontoon, you would need two SI transducers and the SILR Y cable.

If you get a MEGA SI unit, those transducers are $350 MSRP.

Yea when i bought the unit i was ned to using a fish finder. I have learned alot about them. do you think there is a bog difference between the 10 and 12 ?

yea pisases me off the pixel is the same for the 5,7 and 9 models.

The Helix 12 has a higher pixel density display than the Helix 10 by about 1,400 pixels per square inch= more HD. The 2" larger display is the biggest difference.

I just reread this man the typos, sorry!