But the 540E does work at the engine peak torque, give or take a couple RPMs. The charts from Cummins vs Kukje for the A1700, doesn't quite match exactly, which is fine.
On the fuel consumption, the difference is quite substantial.
Last week I decided to do the first pass of tilling in 540. I could almost see the fuel gauge dropping but on the other hand, the engine got much quieter and smoother. I've never really revved up much higher than 2000 RPMs, other than the occasional road trip to get hay for the goats. It was a nice break in process.
The second pass at 540E, the fuel gauge will take a lot more time to drop.
EDIT: But the absolutely best thing of the 540E, is that you'll then have a Neutral position in between 540 and 540E, which lets you rotate the PTO shaft freely to align the spline when hooking PTO implements. This is an huge advantage versus single PTO speed tractors with electric over hydraulic engagement and it's often an overlooked feature.