I think a portfolio site is more to show off to domainers. I don't believe showing end-user (prospects) your whole portfolio is helpful unless you have like 100k domains and look like a big biz doing it that way.
I have tested some different ways and now I have all my domains forwarded (yes forward, I don't like the nameserver pages) to Afternic.
When I am talking to some end-user about domains I send them to one of my other websites which is not a portfolio site.
So maybe you really want a portfolio site, but like I'm explaining, maybe you shouldn't show off all your domains to buyers...
I just recently built this one website to show endusers about domain names in general and appear legit (LOL) www.tld.ltd
So that there, not a portfolio but instead some little info page to convince them of domains in general IMO. Looking less desperate, mysterious etc.
check out media options - I've always liked their site..
I personally believe that you have to give an option for a person to buy the domain on the spot. All out LL domains redirect to the relevant gtld category on our website and a user has the option to buy it now.
for example, jn.be or cp.be are redirected directly to LL.be category on our website.