You might want to switch to actual straight track and see if that improves the pulling power up the hill or not. The various small gaps in the flex track could be letting the train motor wheels slip too much.
I have all the PF track from the Red and Yellow Cargo trains, I'm a 9v guy and thus it doesn't hold much use/interest for me. If you'd be interested in trading for it, I'd certainly entertain any offers.
I bought mine a week or so ago, the Lego store only had the 3 left on the shelf. If you plan on getting this set, I would act sooner rather then later.
This is a little belated, but better nate the lever..
I've always had a soft spot for lego trains, never had em as a kid. Finally found a 9v set for cheap and it brought me out of my dark era.
I added to my collection today, I bought 3766 and 7939. I need to update my signature image.
You might also want to open the motor up and apply some grease to the axles/gears inside.
http://www.trains-n-town.com/forum/viewtopic.php?showtopic=1154
You should also modify the Emerald and remove all the internal gearing on the wheels, it will reduce friction.