I'm in a similar situation meself. One of my tasks at the boat show was to visit the main manfs. & see what they had to offer, Raymarine, Garmin, Navico, without exception they all advised against touch screen on an open RIB. They didn't say that it wouldn't work, but they couldn't guarantee that it would, especially with gloves. I know some people have had no problems with touch screen & others that have had. On the Round Ireland race
challenge there were a few problems & those conditions were about as extreme as it gets. The Raymarine hybrid touch allows you to swap between touch/ non-touch, but you need to sell a couple of kidneys & your first born to buy a decent setup.
I'm currently leaning towards Lowrance non touch, but I'll see what comes out in the next few months.
I'd echo the thoughts about size though, as big as you can afford/fit, even better, fit a pair