Also, don't forget that polls mean nothing. Seriously. First Strike is a sci-fi mod, bf2142 is a sci-fi game. Many people don't like sci-fi, and therefore wouldn't play first strike or 2142 so those people aren't lost since we would never have them in the first place. People who do like sci-fi, however, are more likely to get 2142 and are also more likely to play first strike. You never know, we may release for both games or just for one.
On the subject of the engine, it may be the same base engine, but they've "tweaked" the engine and added new code so it isn't truly the same anymore.

Arrgh, yar... arr ar arrgh!