Nice write-up.
I considered a Vette when shopping for my Z4M, but kept thinking it was just a bit too big.
As for the 1-2 shift... it's notchy and takes some getting used to on all Z4's. Just don't rush it, and almost exaggerate the steps. Once in 2nd it's all smooth sailing!
If you decide to do exhaust, Remus is known for being one of the least aggressive (in terms of loudness/drone) options for BMWs.