Compared to a Mini 9:
Most 1010 netbooks have slower CPUs, and the 1010 has a very slow IO interface, but the 1010 should be faster for video decoding.
The 10v/1011 is equal, but has a slightly faster optional CPU, and can be outfitted with faster SSDs.
The 1012 and 1018 are slightly faster, and should be able to take advantage of even faster SSDs than the 1011.
But no single core Atom CPU netbook will be an earth shattering upgrade. I have a 1012 and a 9. The 1012 has a much faster SSD
, which is noticeable at times. But much of the time, performance is similar.
If you want a serious upgrade, while still staying small, look into dual core "netbooks", like Intel's CULV models. This includes the Inspiron 11z.