Unfortunately, some modern engines seem to have a very strange EPR derivation. On the RR Trent as fitted to the 777, you can be at a constant speed and altitude with <1 on the EPR gauges...
On other types I have flown that would mean drag. Personally I use N1 as it seems to be far more related to the thrust produced.
In the good ol' days on the clockwork 737 EPR really seemed to mean something - you could get very close to the required thrust setting by doing some mild mental arithmetic with the a/c mass. If you lost an engine, you just took the bit after the decimal point, then added it to the remaining engine. 2 x 1.4 = 1 x 1.8. Simple! Doesn't seem to work like that now...
