@Mihai yes you are right

@Mihai
you can attach analogue sensor to ESP2866 with espeasy firmware ... more info here : http://www.letscontrolit.com/wiki/index.php/ESPEasy ... i'm using one ESP8266-12E and i have good results and Uptime: 74209 minutes (usb powered).
i'm using IRQ on NRF24L01 connected to my Rpi, but i don't have many sensor with nrf+arduino (only 2) and i had no problems ... i don't if IRQ improve the reliability and i never play with irq fron nrf on arduino.
regarding retain=true have a look here : http://www.hivemq.com/blog/mqtt-essentials-part-8-retained-messages
for more reliability on mqtt i think you can use qos=1 ( The broker/client will deliver the message at least once, with confirmation required.), but all depends on your set-up .. not all messages need special attention.

@Mihai

Maybe i'm wrong but IRQ is used on all gateways if you read above :
"""
Improving throughput for nrf24
There is another method were the interrupt pin from the nrf24 modules is used to inform when a new message arrives and it's immediately added to a queue for further processing
"""
for the second part yes you can use other pins on RPi ... i have RF module NRF24L01 for gateway and DHT11 on RPi.

@Oli see commands above how to Install and Build, with git checkout master you are on master if you :
cat README.md
MySensors Library v2.1.0

default on git clone you are on development :
cat README.md
MySensors Library v2.2.0-beta

@Oli ... try :
./configure
make
sudo make install

@marceloaqno
i've tried on banana pi pro :

cat /etc/debian_version
8.6
cat /etc/bananian_platform
BananaPro

@marceloaqno

git clone https://github.com/TMRh20/RF24.git
cd RF24
./configure
[SECTION] Detecting arm compilation environment.
[OK] arm-linux-gnueabihf-gcc detected.
[OK] arm-linux-gnueabihf-g++ detected.
[SECTION] Detecting target machine.
[OK] machine detected: SoC=A20, Type=unknown, CPU=armv7l.
[SECTION] Detecting DRIVER
[OK] DRIVER detected:SPIDEV.
[SECTION] Detecting OS.
[INFO] OS detected:LINUX.
[SECTION] Preparing configuration.
[SECTION] Saving configuration.
[SECTION] Cleaning previous builds.
[OK] Finished.

make
arm-linux-gnueabihf-g++ -fPIC -march=armv7-a -mtune=cortex-a7 -mfpu=neon-vfpv4 -mfloat-abi=hard -Ofast -Wall -pthread -c RF24.cpp
arm-linux-gnueabihf-g++ -fPIC -march=armv7-a -mtune=cortex-a7 -mfpu=neon-vfpv4 -mfloat-abi=hard -Ofast -Wall -pthread -c utility/SPIDEV/spi.cpp
arm-linux-gnueabihf-g++ -fPIC -march=armv7-a -mtune=cortex-a7 -mfpu=neon-vfpv4 -mfloat-abi=hard -Ofast -Wall -pthread -c utility/SPIDEV/gpio.cpp
arm-linux-gnueabihf-gcc -fPIC -march=armv7-a -mtune=cortex-a7 -mfpu=neon-vfpv4 -mfloat-abi=hard -Ofast -Wall -pthread -c utility/SPIDEV/compatibility.c
arm-linux-gnueabihf-g++ -fPIC -march=armv7-a -mtune=cortex-a7 -mfpu=neon-vfpv4 -mfloat-abi=hard -Ofast -Wall -pthread -c utility/SPIDEV/interrupt.c
[Linking]
arm-linux-gnueabihf-gcc -pthread -shared -Wl,-soname,librf24.so.1 -march=armv7-a -mtune=cortex-a7 -mfpu=neon-vfpv4 -mfloat-abi=hard -Ofast -Wall -pthread -o librf24.so.1.2.0 RF24.o spi.o gpio.o compatibility.o interrupt.o

also on banana pi pro when i trie to compile i'm getting this :

[SECTION] Detecting target machine.
[OK] machine detected: SoC=A20, Type=unknown, CPU=armv7l.
[OK] init system detected: sysvinit
[SECTION] Saving configuration.
[SECTION] Cleaning previous builds.
[OK] Finished.

type i think must be BananaPro

on make :

-o build/examples_linux/mysgw.o
In file included from examples_linux/mysgw.cpp:74:0:
./MySensors.h:258:2: error: #error No support for nRF24 radio on this platform
#error No support for nRF24 radio on this platform
^
In file included from ./drivers/RF24/RF24.cpp:23:0,
from ./MySensors.h:294,
from examples_linux/mysgw.cpp:74:
./drivers/RF24/RF24.h:52:17: fatal error: SPI.h: No such file or directory
#include <SPI.h>
^
compilation terminated.
Makefile:98: recipe for target 'build/examples_linux/mysgw.o' failed
make: *** [build/examples_linux/mysgw.o] Error 1

so Banana Pi Pro soc A20 it's also on wait list or never worked ?