I've seen benchmarks indicating that the WBK-38 and the earlier FOP-38 are close to identical.
I recently replaced an Alpha PEP-66/Delta 38 HSF with a GlobalWin FOP/Sunon 42.5 cfm 80mm case fan HSF. My Slocketed P3E 600 @744 is now about 1C hotter than it was with the Alpha/Delta 38 combo.
After seven months of listening to a Delta 38, it's worth the extra 1C! Summer may change my mind about this, we'll see.
If it helps, I changed out my stock HSF for a GlobalWIN FOP38 and my temps went from 55C idle 60+C load to 41/42C idle and 48/49C load... yeah, it's still warm, but it's a 1.33 running 1.46 so I guess that's not bad...
The Swiftech 462-A is indeed the king of forced air cooling for Socket A processors. Better make sure that your particular mainboard has the four holes through it that are a must to mount the Swiftech beast-- before buying one.