In this rare instance I think I'll try speaking for Patrick McKenzie, a fellow consultant, along with myself: we think the answer is the latter.
If you're aiming for the most lucrative work, the conversation you want to be having with prospective clients has very little to do with anything you'd put on a developer portfolio, and a lot more to do with (a) being able to speak the language of business (ie: making a credible benefits-focused pitch and understanding how "customer service" principles apply to our kind of work) and (b) being able to tailor a case study or two to a client.
The latter might sound like something you could profitably host on a freelancer site, but the kind of case study I'm talking about works more like a resume cover letter than the resume itself.