Earlier quoted context omitted.
If you have a lot of domains (or willing to pay a premium), I am a huge fan of Fabulous.com. Good support, good pricing, my impression is fairly secure. They have an executive lock feature: Executive-lock (E-Lock) allows for the domain name to be frozen. This means that the domain name is: 1. Unable to be transferred out to another Registrar. 2. Unable to be pushed to another Fabulous account. 3. Unable to have chang…
Holy cow: "If your portfolio generates US$750 a month or you are willing to transfer 750+ domains to Fabulous, please complete the form below." That's a little out of my range though I'd be willing to pay a premium (how much of a premium?).
They are focused on large portfolio customers. That's kind of the caveat for their service. Many of those large customers also use their other services like domain parking too.