"I really love that there is no extra weight on the Alexa (Preston brain)" "you will be happier and your back will live longer!"
Something that is often overlooked:
(apart from an Alexa Studio, as it is always a Plus camera) On other Alexas the Plus is heavier than a non-Plus: e.g. Alexa XT = 6.6kg, Alexa XT Plus = 7.3kg. Thats 700g more on the camera body to get the integrated system working, which is heavier than a 3 or 4 channel Preston MDR.
There are also options for motors that are lighter than the standard Arri CML4s, etc. Even using the Arri UMC4 system (external brain) on a non-plus camera is significantly lighter. And you can run a single channel system for even less weight.