I have a Linux hub, and I just want a reliable means of talking from that to a bunch of nodes which control hot water, heat,etc. I want the nodes to be as reliable and autonomous as possible, ie just my own bare-metal code, so I chose Arduino. MQTT is the protocol for comms, so my iOS and Android speak MQTT to the Linux box (running MQTT broker - Mosquito) and the Linux box broadcasts MQTT messages, which the Arduino nodes listen for and respond to.
At current moment I'm running almost the same, but instead of MQTT broker I'm using Domoticz on Raspberry.
It's open source and people on forums are working with MQTT integration to it.
My current interface is MEGA with RF24(Network) nodes all over house.
I'd like to (if it's possible) to look @ your code and maybe find some inspiration with switching to complete-MQTT with nodes and MEGA.
The RF24 limitation is 24 bytes in one message, I'm not that good with thinking how to program it to get messages queued od sent-together other way...