There are a couple reasons why I tried this 2 channel design.
The Mini^3 was a design by amb and morsel, used with permission. I wanted to break away from borrowing someone's design into standing on my own two feet, so to speak. I know it's more or less a Cmoy circuit, but I still have some curiosity left in me to play around with different designs, even if I re-invent the wheel a little..
Also, it's a hypothesis to see if the difference in sound signature feels better to me from a rolled opamp, two channel perspective compared to a fixed, three channel design. After hearing the Senn Orpheus for the first time, I realized that I'm not the type of listener to value accuracy above all. I like my music to get me moving, so I'll do that with equalizers, headphone mods, component swaps, or whatever I can get my hands on in a pinch. I'll stream music on YouTube, Spotify, sing along to CDs in the car, go to concerts and music festivals, and in plug my ears in a small, packed night club. I hated my brother's Etymotics for their uninvolved clarity, and I loved the few minutes I had with a friend's punchy Beyer T1s. I listen to my PortaPros unamped on my walk to work, and I got a powered USB hub just to amplify music with the Carrie Amp directly from my iPhone. That is, I'll go nuts getting the right sound, but I'm too practical to focus purely on reducing THD.
I like the splashy, messy Grado front row seat sound, and I like the HD650 minus the veil. I think innovation in hifi audio can mean fancy circuits as well as doing the same thing in a different way. Think of a restaurant doing burgers, hot dogs, and fries. They aren't inventing new food groups or item menus, but they could bring something new to the table by doing it in their own way. JDS Labs found success doing a Cmoy with bass boost, and I'm doing it here with socketed single channel opamps, star ground, and a ground plane. I'm not sure whether it'll measure better or worse, but I'm still in search of that perfect sound signature for me.
It may not make total objective sense, but I'm just trying to follow my ears.