Alita 40 for 12 sponges? Heck yeah! In fact an Alita 40 seems like big time overkill to me. Look at the Alita AL-15A. It would save you at least $40, and give you enough air power to do several more sponges if desired.
Now if you are adding another rack later, then you may still want to look at the Alita 40 still. I have an Alita 60 running 4 racks with air to spare.
Several factors are still are involved though. How much air going through the sponges, vertical location of sponges and tanks, and hose lengths. For example, it's tougher to pump air down than up. That's why I have my pump on the floor. Yadda Yadda.
The Alita 40 has 48 lpm @ 2.18 psi, while the Alita 15A has 20 lpm @ 1.4 psi.
For comparison, my Alita 60 has 68 lpm @ 2.18 psi, but as you can tell the only difference between the 40 and 60 is the lpm.