Loved that road. And I'd enjoy seeing a 4C Spider vs. 124 Spider comparo.
I have driven both. They both offer a fun driving experience. The 124 is the more practical of the two, but the 4C is in another league in terms of performance. The 4C is essentially a full on exotic car just scaled down a little.
The 4C has a carbon fiber chassis and a much better engine. The 124 has a trunk you can use, it's easier to work on and has a darn good engine. In any performance contest and stock vs stock, the 4C will beat the 124, but at a much higher price. I guess the way I see it is this, the 124 offers about 90% of the fun for about 1/2 the price. Now that I think about it, that's often been true when comparing Fiats and Alfa Romeos.