I just had and RL70CRC+ installed in my new catalina 350. The color display is the way to go. I also put a 2KW Raymarine radome on the mast and the Raystar WAAS 120 GPS Ant. on the stern rail.
Wow!! C-Map NT and full color display is just amazing. The system is incredibly accurate. I used the RL70 to take the boat out of the harbor Saturday night. I had marked waypoints on my way in the week before during the day. Good thing I plotted the waypoints next to the bouys not at them cause'' I would of hit them!! The 7" screen is fine. I also have the 5000+ auto pilot and full compliment of ST60 instruments. The auto pilot head and ST60 instruments share a horizontal Nav Pod. The RL70CRC+ is mounted in an Edson pod above the ST60 rack. It looks and performs great.
I am an Airline Transport Pilot /Flight Instructor. Eye scan plane or boat is very important... (boat in low vis.conditions or at night). Design your electronics on your ship accordingly.
I do highly recommend the 7" RL70CRC+.
Best of luck what ever it is you install.