Another member here recently just purchased new a SIMRAD
GO7 XSE TotalScan 7" Multi-Touch Chartplotter with Built-In Sonar, wi-fi, charts & GPS for £400.
With that it's hard to ague that new tech is too expensive compared to buying old tech. You can easily connect your motor to it for a full engine monitoring panel. With the new touch screen models you're also buying into better and easier connectivity to other equipment and more features on one monitor (if thats what you need).
They (Simrad) are getting good reviews with no comments about wet touch screen issues, not to say it can't happen. It pretty impressive what it's capable of and would work nicely for a rib. It can kill many birds with one stone and help save on the very precious and limited space on a center console. I do use a lot of Raymarine chartplotters and would much prefer using the newer Simrad touch screen by leaps and bounds. Touching a new waypoint ahead of me on the screen or changing the route on the go is priceless to me.
I can definitely appreciate the question and concerns of using wet touch screens. I will say using gloves designed for iPhone use greatly helps in cold wet weather. I regularly have to use a touch screen cell phone on a rib while working, it's only an issues about 10% of the time and the newer chart plotter touch screens are superior in the wet compared to my iphones touch screen in the wet. Using the lock screen for a quick wipe if needed is easy peasy.
Nothing wrong with buttons if that works for you and your content with the old tech and limited options, they do however take up much more space.