OK, so if you sold 7 hand regged domains already then you know what this guy said is BS!
Every domain that is registered is a premium domain, because you most likely would have to pay more than the registration fee for it. Which makes it a premium!
Just keep this in mind:
90% of "domainers" just don't know what the hell they are talking about.
5% of domainers know the truth, but wont share it with you.
5% of domainers know the truth and try to tell you if you choose to listen.
Remember this also, almost EVERY domain was "hand registered" at some point. Keep that in mind. And, don't listen to the BS, do what works for you...
You could go around buying "4-prems" or whatever for $x,xxx+ but at the end of the day, you are left with only domainers to sell too, because most end users could give a sh*t about a domain being 4-prem, keyword this, or whatever.