I spent the time in reading all these posts related to geometry settings. I don't own a 4C yet but I played with geometry settings a lot on my current car and I currently have camber = -3.5 grd
I looked at alfa OEM geometry values and to me the TOE looks too open --> this would determine a tendency to turn with a minimal steering adjustment but I don't think it behaves that well in the bends nor straight lines. Probably the tires would wear on the inside in some cases.
Anyway, below are my findings so far with geometry settings on my current car and some may apply in alfa's case too:
1) Adding camber drastically improves the handling in bends. For an alfa driven only on the roads I would go with a setup with -1.5 to -2 grd of camber. TOE should be adjusted to generate even wear on tires + confidence when turning and high grip when turning. FORGET ABOUT OEM TOE RECOMMENDED VALUE!!!
2) As Jamie said before: I would first adjust the car geometry to make it behave properly before adding a suspension. A proper geometry can make huge improvements in performance and worth any penny invested.
3) I would try to find a proper alignment service. Those with laser adjustments (sometimes called 3d - 4d - ... are designed for fast adjustments (to make more cars in a certain amount of time) and sometimes the level of deviation accepted is not ok.
4) Did anyone here modified the geometry (TOE to be precise) before fitting Jamie's blocks? --> Like making the TOE closer to 0 grd? I am confident that even without Jamies blocks a proper TOE value can improve the car a lot.
5) In any case (see point 4) in the end I would still buy the blocks and tune the car to behave like it should (after all is a 900 Kg CF chassis that should destroy on the bends any car).
6) Tire wear --> Even with high values of camber if you properly adjust the TOE, the tire wear will be uniform. Basically: in the bends you need to keep the entire surface of the tire on the pavement because this will generate grip. The harder you take the turn the bigger the tendency of the wheel to lean --> The negative values for the camber basically cancel the wheel leaning when taking a turn.
7) Did anyone tried some really sticky tires with this car? Like slicks or federal fz 201 ? How does it behave ?
Ultimately, even though I understand that Jamie provides a "new value" for TOE different from OEM and tested by him, I would recommend for those who alter the camber to also make a few visits to an alignment center and modify the TOE value. Start with the recommended one and add / remove ~0.05 grd just to see what happens and maybe improve the handling.
PS: I'm anxious to buy an 4C and do all this tests myself