Thanks for everyone's responses so far!
The way I tested this is, I created a simple rule: when a virtual button is pressed, turn on/off all of the switches:
How can I know whether the devices support this or not?
The following is one of them:
Update: okay, I installed your driver and the following are the results after running some of the scans; I suspect the device does not support association group?
My house is surrounded with metal beams (something like this); I wonder whether this has caused the zwave frequency to work slower in my house.
Interesting enough, when I created a similar rule for zigbee devices, it works instantaneously and sync'ed properly.
I personally like zwave devices (even though they are pricier) than zigbee, because it allows you to set more granular settings (such as the ability to always-on power failure recovery, power monitor, etc); but this delay rather defeats the purpose.
Thanks for this extra info
