sorry, that's the standard response offered up by everyone based on hearsay,
I wouldn't say it's just hearsay... it may be often-repeated, but the basis is shared experiences. When the Apex & EB8 first came out, there was quite a bit of sharing in this regard as I recall.
That said, byronsands, I do like your idea of a list - with some reservation. Maintaining such a list is going to require commitment. Are you willing to step up to the plate? If you are, great! It may be a challenge though... for example, there could very well be conflicting reports for the same device (due to variations in TRIACs as kurt_n mentioned, due to revision of a specific model of device, etc.) To maintain such a list properly, you'd need to track both yeas and nays. You'd also have to determine that each report is based on testing with either an actual EB8 or a DC8 (there still are many many of those in use, some on Apexes), dealing with the fact that people here frequently use the terms DC8 and EB8 interchangeably. Personally, I think it's going to be an exercise in futility.
If you do opt to take it on, I can contribute one entry for you: my Koralia Nano 425 (rated @ 3.5w) does not get shut off reliably on any of three TRIAC-based EB8 outlets I tested.
Folks, there is more to this than just the load in watts... the power factor of the device and the type of load (i.e. resistive or inductive) do have an affect on the ability of a given device to be reliably controlled by a given TRIAC.
The simple 5w rule of thumb *is* a solid guideline
for dosing pumps & powerheads plugged into an EB8 (as is the similar 10-12w guideline for the older DC8). Results with other types of devices, such as CO2 solenoids, may vary widely. For example, a while back I ran a test (OSC ON/OFF every 5 seconds) on a nightlight (LED-based, I think - it just gives a greenish glow) that draws a whopping 0.3 watts (no typo - zero point three) - I watched the nightlight for a few minutes - it was operated perfectly. Likewise, a 3w incandescent lamp worked perfectly. And I know that there are people running solenoid valves with miniscule current draw (like 3w) which do operate reliably. Another example... the K-Nano 425 I mentioned above, when plugged into an "outlet saver" pigtail with a tiny embedded LED (like the pic below), does work 100% reliably for me. Others have tried the same or similar pigtails, but it didn't make a difference with the devices they tried. Bottom line - YMMV -
always test.