RMS arms are known for it’s slight droop. The droop angle seems to be the same regardless if mounted with ReeFi Duo Extreme/Deluxe or Radion LEDs.
ReeFi Lab has added an option to correct for this 3.6 degs droop with using RMS Mount Adaptor for ReeFi Duo Extreme/Deluxe LEDs.
ReeFi Extreme in the front is using RMS Mount Adpator with 3.6 degs correction and back unit is no correction. 
RMS Mount Adaptor with 3.6 degs correction results with bubble leveler
