After flying this plane for a few days and poking at the PDCS (which only crashes the game if you are mean to it and press the buttons far too many times, just be gentle with it and it's pretty well-behaved) I think the numbers it generates for EPR are "accurate."

If you use the FDE mod found on the forums here the numbers are pretty spot on for cruise (once level at cruise alt) and take-off (note that if you do reduced power takeoff for 80+ F you're looking at about a 1 mile takeoff roll :) ), but they're incorrect for climb and cruise when not at cruising altitude.

The problem with climb and cruise before you're in level flight are the fact that the FL and TEMP pages don't work correctly.

From what I can see, what the FL submode should do (note that this is conjecture having never actually operated one of these units) is automatically determine the optimum FL for the selected "speed" (ECON or LRC) based on gross weight which will then feed into the CRUISE page so that when you select CRUISE ECON you get the correct EPR for cruise at that altitude. FL MAN should let you set a FL for CRUISE MAN which would then calculate the correct settings for cruise at your selected FL.

The TEMP submode should automatically calculate the TAT (and TAS, and all that other stuff, but those aren't really all that relevant for what we want) which will then feed into the CLIMB page and thus give us the correct derated climb EPR based on TAT. You'll note that the CLIMB page always gives 261/.72 and 2.18 EPR for climb power, the speeds are probably pretty decent in any conditions, but the EPR is too high until the TAT drops below about -10C.

Again, these are my conjectures based on what it seems like this unit should do, not any actual experience having used one of these.