I don't believe a standard GTi is better at going round corners than the Ed30, but I do think the Ed30 could be improved on with the bigger brakes from the Leon Cupra and bigger intercooler from the S3.
I wonder how the new Impreza STi would fair round the same track as the Edition 30? One would have to assume that they would be closer time wise with the bigger bhp differential, the STi's bigger brakes etc.