If you want to do a 4-stack, I'd recommend you use the modular cabinets and ask Jay to do a top plate that is the same size as the cabinets (no extra overlap). These have a nice reveal between each separate woofer box and will also have one between the top box and top plate. I think this will look a lot cleaner and more modern than the larger top plate overlap.
Mine are currently built with the larger top plate and I've asked Jay to make new top plates for me that are the same size as the cabinets.
The modular design is a lot easier to move if you need to relocate your woofer towers. The four stacks weigh 200lbs+.