ok....i know i may come off as fanboy....but i have a 5 reply email with scott about where they stood in comparison with RE.....
the X is like the RE RE but with more power handling...so maybe like the RE SR?
the SSD has SQ in bewteen the SE and SX....and output a little below the SX with the regular coil. with the Flatwind coil(increasing the power handling) it moves up to the output of the SX.
the Q is like a 05 XXX, but louder on par with the SQ.
watt for watt, the SSD will get louder than the Q with the flatwind, but once it runs out of Xmax, the Q takes over
BTL i have "heard" is like the RE MT with more SQ....and those things were crazy loud so go figure...