Arrangers could also utilize new storage technology such as SSD (solid state drives). That way you could stream live content, such as VSTi's (virtual instruments) for sounds and even videos which could then be routed to an external source during live performances. Audio Drums and audio Styles are nice but having the ability to stream live content could revolutionize the industry.
The SD7 is all of the above. It has onboard Solid State storage; Not sure how much, there is 8.5gb used from the factory and 92% free. You can also install the optional 250gb SSD if more space is required
The SD7 displays video, images, text or PDF files to an external digital projector or screen via the DVI-I port on the rear (great if your into Kjay). You can mirror the on board screen or display other content to your audience.
I am not certain of the speed of the SD7 USB, I backed up all 8.5gb to my laptop in just a few seconds.
Dont forget with newer Ketron products, polyphony is not so relavent because aspects that use polyphony in other manufacturers arrangers (styles) are live and so do not use the built in sound engine. You have to use some serious sustain and alot of layers to run out of polyphony on a modern instrument. If you are that specialist and require more than 128 notes (unlikely in my oppinion) Ketron offer additional sound modules (eg SD2/SD1000) for little money that could be used easily with your current arranger.
Regarding Sequencer, with so many good quality (and low cost/free) sequencer programs available on PC, Mac, Linux and probably even Android, Ketron felt it was no longer relavent on a modern arranger. Some will no doubt disagree but but these are a minority and the majority will be happy not to pay for the development of software they are never likely to use.