Never heard of Emerald before.
For off-road use, you can do better though. You'll want knobby tires and fenders.
Remember to look at the weight spec too. To me, a folding bike that weighs 65+ lbs. is of limited value, because it's so hard to lift.
The Lectric XP Lite weighs 44 lbs, so it's liftable, but is only a single speed. Fenders are available for separate purchase and it'll still come in under a grand. Good quality, too.