This was mostly around interfacing, or getting 1kw transducer power to the transducer. Raymarine have them, but, if you buy the RVX version of the Axiom ( otherwise known as Pro), you get the CP-470 1kw module built in, and they network together with nothing more required than a Seatalk cable. Personally, I would steer away from pure touch screens for a boat. Wet fingers and a rolling boat can be a very frustrating combination--fine in the shop, but you get my drift. I have one of each networked together, and I can tell you what is superior. The Hybrid Touch system on Raymarine Axiom ( and some earlier models) is very good, configurable buttons, and ability to use either a button/knob or a screen touch, your choice. 

If you want any info about the Raymarine system, go to the Sounder section and the Raymarine thread, I have actual screenshots and feedback, rather than someone's second hand opinion on it. I'm happy with mine, after 2 1/2 years and 650 hrs, fished everywhere from the shallows of Shark bay and Exmouth gulf out to 320 m bottom bashing and 1000m chasing marlin.

 If you are not using a screen designed for this application you may have trouble viewing it if the sun is on it.