They're testing out 6tb drives early, so when the time comes to fully switch over. They know what drives to get from what manufacturer. They'll also have a better idea when to switch over.
But the whole problem about Reddit has with getting ad revenue with a current system, is the users. Users on Reddit arent interested in advertising as it stand online. Like a lot of Internet users. In my opinion the majority of adverts online are a waste of time, money and space. I dont think I've ever bought anything spurred straight from an advert, though I buy plenty online. It's nearly always something I've wanted, then researched.
I guess I view this separation as an adaption of The Single Responsibility Principle. This is how I view themes & plugins, and their relationship. Your theme is used to display your site, it's navigation, content, it controls the markup browsers see.
Plugins are for adding functionality to your site, if you want a sitemap, there's a plugin for that. Not happy with your current sitemap? Install/Create a new plugin, replacing the old one. If your sitemap isn't working, where do you look? Your sitemap plugin's code.
The importance of having this separation of tasks, removes a lot of risks too in my opinion. If your site isn't working instead of risking having to change your theme, you can deactivate the troublesome plugin. Albeit finding the offending may be difficult, but at least you're not changing the total design of your site.
Hence why I believe in plugins and themes having distinct tasks. It really helped me organise the development, and maintenance of sites.
I've been following Gittip's progress for a while, as a student funding someone through this isnt a priority for myself to be honest, I've started working now though so I'll have no excuses! Though I think the name means nothing to people outside of tech. I guess the decision to change the name depends on whether you're targeting nontechnical people who appreciate a developer's work.