I have the maxed out 16" pro (except for the 8tb SSD). No clue on fan noise, I don't pay attention to it. It's completely normal for fans to kick in when doing processor intensive tasks and I'd rather have that than throttling.
As for speed, its super fast. Everything compiles and starts up near instantly even on large projects. I think it's a great development machine.
And I know this is a mental thing, but the extra .6 inches just feels like 5 extra inches when working only on my laptop. At first I didn't notice it too much until going back to my work machine (a 15.4). The 16 inch is great to code in.