Oh, nice. Good to see I'm not the only one still holding on to their X58 platform. I'm not too concerned with the performance of the units. In my case, I switched the cooler on my i7-920 @ 3.5 from a Cooler Master V8 to the Kuhler 620 and am getting similar numbers. I've got a relatively low airflow case (NZXT H2) and using the water cooler gets heat from the CPU straight out of the case, where as the tower cooler, although more substantial, was recirculating the air and more vulnerable to hot air from my 2 GTX 480s that escapes the side of the shroud near the expansion slots.
I replaced the Antec Kuhler included fan with a PUREX brand fan from Micro Center. It was cheap ($8), my Micro Center was out of the Corsair high static pressure fans, and no other fans there offered a decent pressure rating. It advertises 32dBa, 72 CFM, and 2.1mm-H2O. Can't really verify those but the thing moves air through the rad a lot better than the NZXT Case Fan, Aerocool Shark, Antec TriCool, and the included fan. I've got a push pull setup on my brother's using the 2 BitFenix 120mm that came pre installed in the Prodigy.