I'm no FPGA expert but I think two problems would be the 4K per-processor memory and the inter-processor communication. You might have routing problems with the

I'm no FPGA expert but I think two problems would be the 4K per-processor memory and the inter-processor communication. You might have routing problems with the Connection Machine's hypercube routing. Random Connection Machine fact I found on Wikipedia: Maya Lin, who designed the famous Vietnam War memorial in Washington also designed the exterior of the Connection Machine CM-5.