Without testing, I wouldn't say one way or the other is better. Adding width only at the rear might make the car quicker. I'm just thoroughly unconvinced it's a no-brainer.
I think everything I've read is that the V6 and turbo 1LEs get the base SS springs, shocks, bars, and the 9.5" rear wheels. That description makes want to belive that it improves the turbo, but the SS is a different car with 300some pounds hanging on the nose and a ton more power which comes on lineally without occasionally ill-timed, but always laggy boost.
Can we really draw a straight line from a parts bin package like that on the turbo back to what they did for the SS 1LE? With its mag shocks, trick LSD, wider wheels front and rear?
I mean, I don't know. I haven't driven a turbo 1LE, so I can't compare even anecdotally. I want the turbo 1LE really good. I want it to be better than the non-1LE. I'm just unconvinced that it is and I worry a little that it could be slower in an autocross environment.
1LE or not, for DS what the Camaro needs are shocks. If I was thinking about buying one today, I'd talk to Jeff at Pro Parts about theirs. The quickest option may be a non-1LE on those shocks and running 18" wheels.