I've noticed with some of the RGB nodes around the house an annoying flickering problem. It occurs when none of the R G B channels is driven at full brightness. This is especially disturbing when a lower light level is desired.
Tried to find out a reason for this. It was not related to the Arduino used, whether it being a Nano, Uno, official or not. Also not related to using gw.wait or delay in the main loop. Or adding resistors to the fet data pins.
Turns out it is related to the Arduino PWM not being very optimal. Tried to solve the problem by using a different approach, softPWM [e.g. https://github.com/Palatis/arduino-softpwm] but they conflicted with servo library (that uses various timers also, as soft pwms do).
Jeelabs brought a solution; tweaking the frequency of some timers. Just tested it, and seems that the flickering is totally gone AND still the servos AND the MySensor communication works. Very happy with the result.
This is the blog post describing the issue, the solution I used is in the comments http://jeelabs.org/wp-content/uploads/2011/11/8/fixing-the-arduinos-pwm/index.html.
So, flickering fixed by adding TCCR2A = _BV(COM2A1) | _BV(COM2B1) | _BV(WGM21) | _BV(WGM20) to the setup. Will need to update a few nodes now!