FLIR seems to help a lot. My experience with it though is limited. Any first hand comments?
Since our primary use is distant (relatively) offshore fishing with the objective of being on the grounds just before grey light, we travel extensively at night. And most of that is at least 10 miles offshore, often 100 miles or more offshore. Day or night, we travel at 8.7 knots on average.
I feel safer at night, in part because we always have two at the helm at night, vs. only one during the day, and in part because it is easier to see other boats (at least when their lights are on) at night. Radar and AIS are equally effective day and night. (And we keep the radar on during the day but have NEVER been surprised to see another vessel that I didn't see first on radar, so I have quite a bit of confidence in our radar.)
So, the big risk is hitting something that is semi-submerged. Frankly, I think that risk is also greater during the day, due to our use of FLIR at night. Because FLIR works on temperature differentials, even things that are otherwise hard to see (small, mostly submerged, no distinctive colorings) show up readily on FLIR.
And to top it off, we run searchlight sonar, but the problem with that is balls of baitfish often show up as potential collision targets (although they scoot out of the way at the last minute). During the day, we are typically trolling and don't mind trolling right through the middle of those bait balls (unless we see predator fish working it -- then we are more strategic in our approach). At night, we spend a lot of time needlessly dodging those things.