Here while automating I have initially migrated all of the LV outdoor lighting to 12VDC non dimmable LEDs.
Just a post about what I am doing relating to HV LED lighting and asking for a bit more granularity relating to your question above.
I am currently at around 12 zones of LV LED lighting being controlled by one automated switch (UPB). I am heading towards individual automated control of each zone. While I have multiple DIN mounted 12VDC power supplies the draw of all of the LV LED lighting is under 150 watts (best guess).
I am particular about the HV outdoor lighting having used these crystalline candelabra looking clear 40 watt bulbs dimming them to about 25%. I am currently more into the "look" of the light illumination than just power savings. Thinking I am using a halogen 120VAC candlabra bulb today. Here I use mostly clear type HV bulbs for a variety of lighting. (chandelier, table lamps, outdoor decorative HV lighting).
Right now testing 2 Watt LED clear candelabra bulb which looks like the 40 watt bulbs at full brightness. I have tested the dimming of these 2 watt bulbs.
I do utilize the bright light at 100% and typically do dim them at 25%. I am testing dimming these down to 25% using X10, Insteon, Z-Wave, Zigbee and UPB.
Not sure if it'll work and really not into changing a $XX installed automated switch (well UPB) for one that will work with these little low wattage LED lights.
HV LED lamps are not older style automated light user friendly today (well starting very slow).
A single HV dimming switch with multiple HV outdoor LED lamps may work (best guess?)
You do have HV 120VAC bulbs today sold as dimmable and not dimmable (not always documented) and automation switches which work with LEDs or not or work with dimmable LED HV lighting or not. Some switches / combo LEDs doing it better than others. It's relatively new now with the advent of LED 120VAC lamps.