I really think the whole alloy light weight deal is over blown, from my experience. I'm running an all iron engine, block and heads anyway, alloy intake and water pump. "Nose heavy"? It aint, simple as that. Whats way more important is how the car is setup. Right now, I've been running laps on Infineon with SAAC-35. I ran laps on Friday and today (Saturday) and will run some more on Sunday.
The car is 100% neutral, I DID manage to get all four wheels off the track on Friday. Not a spin out, an all but perfect sideways "drift" until I ran out of pavement.
The steering is remarkably light and easy, the tires (WHEN they get hot) stick very well. When the tires are cold, they are just about like street tires, not much traction.
I seriously doubt I could feel any difference with alloy heads. Maybe if I went all out and did the alloy block, etc, maybe. But then the handling might be off, I've have to re-adjust accordingly.
It aint the wieght unless your already dialed in and ready to drive in the experienced class or higher it doesn't justify the additonal expense. That assume's there might BE additional expense over an iron block to begin with. That depends on what the individual has on hand or can get at any given time.
A light weight all alloy engine ISN'T going to suddenly turn you or your car into a great handling machine around a race track. There are other variables far more important.