I have an M590E GSM kit connect to an Arduino UNO and I'm able to light an LED by sending an SMS. I can also connect a button to the UNO which makes the M590E send me an SMS when the button is pressed.
I would like to create a wireless network of 5 sensors (binary switch), which would send a signal to the UNO when pressed, which then would send me an SMS through the M590E module.
What is most advisable to use indoor, 433Mhz modules (FS1000A) or nRF24L01 (hooked to Arduino Pro Minis)?
It would be interesting that one of these modules could be a sensor and an actuator, that is, besides sensing if the button has been pressed it would include an independent relay which I could trigger through SMS. This implies 2-way communication and, as far as I understand, the nRF24L01 would be more reliable to use...
You have not given us any details of the environment in which you want the system to work or the distances involved - apart from "indoors".
I only have experience with the nRF24L01+. Its 2.4GHz signals can be disrupted by the walls of buildings and 433MHz signals would be more likely to penetrate them.
The nRF24L01 seems to be vastly documented unlike the 433mHz units. I am aware of it's performance because the remote control I use for my quadcopter utilizes it as RF transmitter and I can fly it through the house(using a first person view video system), without loss of contact.