I got the chip today, and after a false start due entirely to my foolishness got it working as advertised.
From what I have read so far you can download something like 256 "instructions" to be performed, and I gather you can do something else while that is happening. So if you had to do a lot of complex calculations (eg. on analog data) the chip could be doing that while you took more samples, or displayed the, or something.
The default clock speed is almost 30 MHz so presumably it does what it does faster than you could at 16 MHz.
It also has two 10-bit ADC converters so that in itself could also be useful.
I'll set up some more detailed timing comparisons over the next few days.