The DEOT OS is basically the same as the 0.4 official one, just with a lot of updates already applied. You can do them yourself, but depending on how much you already know about coding etc, it can take a long time. Some elements take hours to build/compile.
In other words, use the custom DEOT image if you want to save some time, and have everything done for you. It will have better performance, and theoretically battery life, since it’s using the dedicated graphics processor instead of the CPU.
That said, it’s like buying the Millennium Falcon™ from Han Solo. It will have a lot of modifications, and goes fast, but unless you know how it all gets put together, it will be hard to make modifications to it yourself in the future.
I like to see the gameshell as an educational device that teaches people how to code, but some people just want a device that can play games and not have to worry about things.
There was talk touched on briefly re: a new screen being looked at. But this was just once a few months back.
I haven’t heard anything official re: a bigger battery, however there are threads here discussing modifying the internal battery case to support a larger capacity battery. Due to the size constraints, it can only hold a certain size.
That said, you can apparently substitute in a Nintendo 3DS battery. Just be careful on two fronts. First, you may find something that is ridiculously high capacity and ridiculously cheap. Chances are, if it’s too good to be true, it is.
Second, pay attention to the wiring of the CPI. There was some discussion re the polarities being reversed.
I haven’t modified the battery in my Gameshell myself, since I haven’t run into and downfalls re: battery life. Don’t fall into the trap of upgrading “just because.” That goes for a lot of things. “If it ain’t broke, then why fix it.”
That said, the very nature of the Gameshell and the slogan “Happy Hacking” certainly does encourage it!
Sorry for the very on the fence devil’s advocate response! Hopeful to this shed a bit of light of the potential and power the Gameshell has!! 