For what it's worth...
Our little group uses HSFX exclusively (coop online missions) mainly due to the variety of machines/connections between us. HSFX seems to be the sweetspot for all participants to play without stutter etc. We have used the Triggers function a lot as well as some elements of the C&C mod (we're nearing the end of a long Battle of Britain DCG campaign at the moment).
During our experience we've found that online some aspects of the Triggers work whereas others don't.
For example:
- simple customized messages popping up at a given point/location have worked almost flawlessly online
- objects spawning based on a trigger have been problematic. Generally speaking, if it is a moving object then it will spawn and online players see the same effect. e.g. fly over a trigger near your base and ambulance and fire trucks will appear and move to a waypoint etc. If it is a stationary object (e.g. a fire, smoke, a light) then it works offline but online only the 'host' sees the effect. For example I tried having a green light appear on the tower indicating 'clear for takeoff' but online only I could see it appear whereas the other online players didn't see it.
The C&C items we have used successfully online (so far);
Chain Home radar - works online, no issues
Ground Observer - works online, no issues
Running figures - works online, no issues
Running Commentary (i.e. Ground Control telling you where you are) - works online, no issues
SAR does not work online or offline (at least in HSFX), as it locks up once you are close to the downed pilot. Pity.