Whille looking trough my MSM pics I found this screen dump.

Section 3 and 4 shows EGT for each runner in a 1.2 bar Rotrex setup. Fuel system is a Walbro 255LPH pump on a stock MSM returnless fuel system including rail using ID1000 injectors.
EGT sensors are Stinger mounted 2" from exhaust ports as recomended in a raceland header controlled by a Innovate TC1 via serial/MTS into an Adaptronic EMS.

As you can see the temps are almost identical at WOT but have som spread at part throttle and idle.  The blue graph showing EGT1 read somewhat lower temps but this can be related to a slightly different angle of the probe in the exhaust stream due to a sharper  angle on the runner/header.

I would say the MSM rail does a pretty good job of distributing fuel across the injectors even with 3x the size ID1000. The MSM rail differs from the other MX5 rails with a bigger "plenum" and a slightly different design.  I couldn´t find any pics but I know there is a thread on Miata.net where it is discussed in detail with pics.  This is however the first datalog with EGT1-4 I have seen on a MSM.