Advice would be to keep RPM below 4000, so you shouldn't have any trouble doing that. It sounds as though ECO Mode is hanging onto the gears more than usual. Not what I thought it is supposed to do.
Here's an idea: If you think that ECO Mode is interfering with your driving intentions, why not turn it off? Reports differ on whether it actually does anything to the engine or if it's just a warning light for dummies.
I would not use the ECO system while in the break-in period (600 miles or 1000 km), you need to vary the speed as indicated in your manual. Wait till its over before trying it.
No its "not a warning light for dummies" it does tweak the engine and transmission for maximum economy, you can tell the difference in the way it drives its more lethargic in comparison to when its off. I've only used it for one tankful so far.