Well, I hope not. The E-Flite Airliner weights about 100g less then the MD80 while having smaller wings and the E-Flite Power Setup seems not to be much stronger then mine. (couldn't find anywhere how many Newton Thrust the Superairliner has) The Plane does not feel underpowered at 3.5lbs/2lbs in the simulator. It reaches 130km/h in level flight and is able to climb pretty steep. I don't know close that is to reality.
If it is to underpowered to take off I should be able to increase the thrust/weight ratio by just putting stronger batteries in. The motors and the ESCs can take more then the two 1800/25C batteries currently in use provide. Again I'm new to this and my reasoning might be utterly wrong.
What about strength for the long fuselage?
The Fuselage is really strong as is. (At least I think so) Lot's of 6mm bulkheads, two 10x10mm balsa beams, three 60x6mm Depron strips at the sides and the bottom and the 3mm EPP-hull make the fuselage pretty stiff. (if you put the backside of the plane on a level table the fuselage will not bend at all)