I don't think I posted a link to Edmunds but in all honesty, I think Lotus' 0 to 60 times are a bit optimistic or are not easily repeatable. I think 4.6 for the Elise SC would be more accurate or at at least more frequently reproduced. That being said, some people on this forum have gotten and posted their 0 to 60 times on the regular Elise which was the same as Lotus' claims.
Also, one factor could be if the Elise SC has the Lotus Sports Suspension (LSS) package with lighter wheels and sticker A048. On the original Elise, Lotus claimed a .2 second advantage with the LSS.
When looking at 0 to 60 times, I think adding a .5 second margin of error help put the cars into perspective and accounts for road conditions and "driver commitment".
In regards to the 220hp Exige S, I'd think it would be a little slower than the Elise SC due to drag and a slight weight increase. But I think the advantage of the 220hp Exige S is that it would be easier to tune due to the intercooler.