I have a smartthings HA system and all my switches/dimmers work great. You can also group switches within the alexa HA section so you can turn off ALL lights in one command.
Also keep in mind when selecting which switches to get... Wemo currently doesn't support 3-way switching which was a big bust for me... I started out with Wemo and bailed on them over a year ago because of the number of 3-way switches I needed to control.