Oh, I meant NS record delegation (I think, terminology might be wrong, it's been a while since I futzed with low-level DNS stuff), so that you could use ns1.mydomain.com as your nameserver, even if you registered mydomain.com through namecheap.
They all allow it - just they don't all make it a simple control panel process. Either email support, or do a search and it can be taken care of on all registrars.
It's not "plus", it's requirement for any registrator, isn't it? I've never seen anyone not allowing to specify nameservers.
It's backwards: "plus" is the ability to have free DNS hosting :-)