Mags are typically more brittle than Aluminum. The old ones, anyway. From what I understand, new ones are stronger and less likely to deteriorate with years as the old ones though (newer/better Mg alloys now).
Also, the RS has higher tire sidewalls than the GT3 which will help absorb some of the impact...
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18 GT3 Manual, 73 Carrera RS 2.7 Carbon Fiber replica (1,890 lbs), 06 EVO9 with track mods. Former: 16 Cayman GT4, 73 911S, Two 951S's, 996 C2, 993 C2, 98 Ferrari 550, 79 635CSi