Nice tutorial...
My approach is a little different but your method might be a little bit faster. First, I install raspbian jessie, resize the partition, configure the window mgr the way I want it then update and upgrade raspbian before the next step. Next, I get the retropie install script, and install retropie. Once it's installed, I just use it to setup my joysticks and to install more emulators. I never even run emulationstation, I do everything through the retropie_setup.sh tool.
The last stage is installing AM by following the attract wiki for the pi.
And, I just wanted to say that it's nice to see someone enjoying robospin on the pi. I made it where you can turn off some features if performance is an issue. But, I've been pleasantly surprised how well it runs on the rpi3.
Speaking of robospin, I've added some new features and hope to release it in the next day or so. It was getting a little stale, so I wanted to add some new features like pan and scan for those who want it. It already has system logos but I thought it would be cool if I could add game logos without creating too much clutter. And, I think that was accomplished. The hardest part has been getting all the game developer logos, I might be short some but most are accounted for.
