Insideline compared the CTS-V sedan with the C63 and M5 over a year ago...
On straight line comparisons, I don't think I have ever seen any comparison where the M3 or C63 has bested the Caddy.
As already mentioned, different track set ups will favor different cars.
Current rides: 2010 CTS-V sedan, black raven; 2010 Cadillac Escalade ESV, black raven
Gone but not forgotten: 2008 M5, metallic sapphire black, SMG; 2004 645ci, metallic sapphire black, SMG