Says the man with the Manson Supreme as his avatar
I've heard that the Delta's design gives it "slightly superior" holding power, but not "substantially better".
Also, I can pick up a used-but-in-great-condition 60lb CQR with 130' of 3/8th BBB and 100' of rope for $300, which is less than the cost of a Manson Supreme alone.
Fortunately, being "hopelessly outdated" doesn't mean ineffective. Thousands of plow anchors are still out doing the job and doing it well. When (if) I have enough "extra" money around to spend on a Manson, I certainly will. But that day will be long in coming.
Until then, cheap, used anchors will have to hold my boat in place. Now I just need to find a cheap place to get them hot-dipped, or I'll be going to the local powder-coating place instead.