They should run just fine. Solstices are direct competition for the Mazda MX-5, and they have been holding their own in auto-x, and they did well at the SCCA Runoffs (Road Racing). Some guy named Rhys Millen drifts one in Formula D and he seems to be doing ok.
Since everyone is using the same car, I think the performance will be fine. I’m waiting to see how much of the suspension they change or if it’s just stock cars and general maintenance.