Looking strictly at the numbers...

The S has a good 25 hp over the Xfire (not counting the SRT6), but the Xfire has a good 70 lb-ft of torque over the S (so climbing up the hill would be easier in the Xfire). However, the Xfire also has a good 200+(Coupe)/300+(Roadster) pounds on the S, so the hp:weight ratio is definitely in favor of the S.

When numbers are reasonably close, as is the case here, it's difficult to make a specific call. However, my money would be on the Xfire taking us off of the line, but the S taking you guys in the long haul if we're able to wring out our engines.

Oh, and Dan... I'm not sure if I would consider a driver (of ANY car, not just the S) chicken just because he doesn't want to race you on the street. Frankly, I'd consider the one who backs down from a street race the smartest of the two