This thread died, but I ran a GP20ECO for the first time, so here are my thoughts. The cab layout could have used some input from those of us who run them. I'll admit that the GP9 fleet was well past it prime, and replacements were necessary. Anything would be an improvement, especially if they had rebuilt some old GP38/40 units, like BNSF recently did.
The units have one FIRE screen. It is below the front engineer's window, with a little table under it, much like our ES44 fleet. The screen should be on top of the control stand. Since these units are used alone on locals, viewing the screen easily in both directions would have been useful. Apparently I should have my DNA rearranged for eyes on both ends of my skull.
The side windows are at my armpit height (average 5'9" build). This is not helpful for leaning out to see motions from trainmen (Most of the new hires don't know how anyway, and the bosses convinced them to use the radio, so they can efficiency test from the office).
The seat lines up well with the post between the engineer's window, and the center one. The seat should be closer to the wall, or even better, the window moved inward some. It gets tiresome leaning sideways to see out the windshield.
The control stand ought to be back some because it would help running in reverse. It should be like the NS sidewinders, which are easy to run either direction.
I already mentioned my dismay at the use of CCB, vs. 26L, or 30 airbrakes, but they are now carded for 184 day inspection intervals.
The radio needs to be at full volume. Even the GP9, with lack of soundproofing was quieter, and more pleasant to listen to.
The light switches have the little icons, instead of labels. EMD borrowed this from Detroit, where the motorist doesn't necessarily have to be able to read. CP might be part to blame because the last few orders have everything labeled in English and French. GE manages using actual words instead of picture icons. The 8900, and 9300 classes of ES44s have the software to toggle the display screens between the languages.
I already has a SD30ECO, and feel they should have just rebuilt the SD40-2 in kind. I'm not impressed! I've always been a big Chevy fan. Until the ES series, the over glorified toaster ovens we're quirky to run, with loading rates measured in millennia. GE has started to get it right, while EMD seems to regress, as far as user friendliness goes.