Been gone for a while...
No explicit, hateful, or hurtful language. Nothing illegal.
Do you know if that's the Ellipsis 8 or 10? Either one should be fine, really.
As for the tablets that work best: for multimedia apps like Synthesia, the iPad easily holds that crown. Things like audio latency (and even graphics hardware) had been an afterthought on Android devices until very recently and even then, they've only been good on the highest-end devices. That said, these days Synthesia is running reasonably well on the Android side of the fence and anything from around Android 4.4 and later will be fine. The real question is whether your device supports "USB On-the-Go" which is required to connect a digital piano.
As for the tablets that work best: for multimedia apps like Synthesia, the iPad easily holds that crown. Things like audio latency (and even graphics hardware) had been an afterthought on Android devices until very recently and even then, they've only been good on the highest-end devices. That said, these days Synthesia is running reasonably well on the Android side of the fence and anything from around Android 4.4 and later will be fine. The real question is whether your device supports "USB On-the-Go" which is required to connect a digital piano.