I'm a friend of Marco's and a member of his group. I've tried the sponge method and it works very well.
A few years ago, many Italian pizza makers started using biga as their preferment for contemporary Neapolitan pizza, something that was not previously done. However, biga is a low hydration (45% typically) preferment and requires a temperature controlled unit such as a wine fridge to ferment 18h at 18C. Not everyone has one of those, and so the sponge is gaining popularity among as an alternative to biga.
Sponge is halfway between biga and poolish in hydration and has a middle ground between the characteristics of both. It's also very easy to mix, and can ferment for couple hours at room temp followed by overnight in the fridge. Because it ferments in the fridge, it starts out cold when you're ready to mix your final dough, so it is very easy to mix the dough without overheating it, even in the heat of summer.
My own experiments showed that sponges have a tendency to create a pretty sticky dough and the final result is neither as puffy as a dough made with biga, nor as tangy and pleasant as a dough made with poolish. It is a bit hard to know when the sponge is perfectly ready for use, and if you go too far, the final dough really suffers. For that reason, I typically prefer either poolish or biga to sponge. But please do experiment with it - it may be perfect for you.