There is more to it than that.

The 2X, while it does have the two extruders, vs the 2 only has one; the 2X also has a heated build plate to allow for printing in ABS plastic. From what I can tell the 2X also has a slightly smaller build plate size, not sure about the height though.

Personally I would go with the 2X because it allows for a wider variety of plastic to choose from for printing. But if you do that, keep in mind that the Makerbot Replicator 2X is being marketed as "EXPERIMENTAL 3D PRINTER", meaning it does have some kinks that will be worked out over time. Personally we haven't really had any problems with ours that couldn't be resolved in under an hour so I still see it as worth it.

Another thing to keep in mind is that the 2X is dangerous compared to the 2. More of the machine is heated and you run a higher risk of burning yourself. I have burnt myself at LEAST 25 times, but it's not that bad. I've never had a blister, it just kind of hurts.