Here is memory:
Internal Storage: SSD Card 16G.
External Storage: Removable SATA 2/3 2.5 HD. USB: 3 Host + 1 device.
Internal is largest of any arranger that I know of, by far.
External is unlimited.

It is quick and easy to save edited styles, registrations, sounds etc.
You cannot save presets (overwrite factory styles or sounds). You just edit them and save to User memory with the same name or pick your own name.
The OS seems very stable, intuitive and fast.
I haven't found any "bugs" that are worth mentioning, but there are some updates and fixes to make things even better, that AJ is working on.