I need just to know which gpio switch the relay, because that's is my main use case.
The olimex board seems well documented and with the schematics where I see that the relay is linked to GPIO5.
The drawback are that is a little bit pricey and that the power is at 5V fixed, but I hope that it will be more reliable and better designed with respect to other esp8266 boards. I'll try it.
For the other board on that announcement I found some documentation too, the cost is similar but the input is variable 7-30Vdc.
Regarding this two board I tought that they are ESP8266 stuff because in their page it is shown that such board are supported by eWeLink App which is the app used by ITEAD Sonoff stuff.
I don't know if such application is written for different hardware or works only with esp8266.
Another clue, for the board "DC-5V-12V-Jog-self-lock-Smart-WiFi-Wireless-Switch-Relay-Module-APP-Control" is that the schematic seems the same of this board: https://www.itead.cc/smart-home/motor-r ... witch.html
apart the single relay. Of course the ITEAD board is cheper and works for sure.