TT, Perazzis are what they are because of they way they shoot combined with the standardization of a high end gun. If the gun has MX-8 type barrels and a drop out trigger it is just another variation. The "slots" you are describing are called side ribs and they are common on many P-guns such as the MX-8. The MX-3 (and Mx-3 special which fits all MX-8 type barrels) had no mid rib. The barrels were separated much like a Remington M-3200. Most modern barrels are separated under the forend and have side ribs in front as you describe.
If the gun has drop out triggers and feels good, buy it.
I love my old doubles, but for serious shooting, nothing beats a Perazzi. And, 2,500 is a good price on one which has not been messed with.
Oh, and I agree that a call to Giacomo is a good idea.
Regards, Jake
