Minni... I have a successful 3 decade experience with B&G so they are my default. I too am not needing all the racing screens and assume that this can be removed to give less clutter. Clarity and proper back lighting for evening is more important to me than screen size because 98% of my viewing is very close. But yeah... it makes sense to built a system with one mfg's components.
I am looking for a way to do this incrementally which I may be able to do as I have one of the 2 MFD plotters already.
The difficult part is installing a new wind instrument, and the radar without taking the mast down... expensive and time consuming. Using the old wind instrument cable I may be able to pull it out from the top with a messenger line attached and then pull the new cable down through the mast... a two person operation. The problem then is to remove the old and mount the new wind instrument. There are 2 bolts on the top of the mast which holds a small bracket and that holds the wind instrument... not something easily done from a bosun chair. I will likely have to have the yard send a man up in a crane to do the switch. If my new radar can use the ex'g mast bracket I can do that install from a chair. Mounting instruments and network cables is something I can do as well.
Night lighting on the Tritons is the best of any out there. It is the only night lighting that I've found to be actually usable at night, and not just an annoying contrivance to save night vision. The Tritons are absolutely brilliant in this regard. They don't so much do "backlighting" - instead they use a completely different color pallete and brightness/contrast. They are 100% readable in a relaxed, normal way - just like in daytime, but with preservation of vision.
If the B&G plotters are the same, then that is a big plus for them.
The Furuno is not so good, neither is the Garmin. Both do the traditional change the colors to muted and lower the backlighting. Both also have inexplicit random bright white elements which are blinding. This just results in straining so much to see the difference between gray, light black, and dark green elements that I just give up and leave it on day lighting with the brightness turned way down. Then put it to sleep unless I'm actually using it. The new Furuno may be a bit better - we will see.
For a wind instrument, you could get the LC Captuers CV7 ultrasonic, which is 0183. Then you could use your existing cable. Inside the boat, you connect up their N2K converter and put it on the network as a N2K device. We just bought one for our boat.
Honestly, a 6yr old can set up a N2K network and connect instruments with hardly any instruction. This is no longer 0183 nightmares of talkers and listeners, breakout boxes, repeaters, mux's, etc. It really is as simple as run a wire and plug things into it. Your entire network for what you want will consist of a few T's connected together, with terminator plugs on each end, and cables from each instrument plugged into them. Attached is a picture of our current N2K "network" (ignore the untidy wiring, I'm in the process of taking everything apart). To pay someone to install N2K is a waste of money unless your boat is a large and complicated network. Then, it is mostly money paid to someone just to snake cables.