DX6, DX7, DX9, DX10T, DX18T, DX18QQ, DX18 and DX18gen.2 are all compatible with the setup files. Obviously the 18 will handle more channels but using them in the 9 works fine.
Download what setups are available here-
Converting SPMs between DX7s/DX8 and DX9/DX18Edit
Models can be transfered between the DX7/DX8 and DX9/DX18 using the following conversion tool:
Conversion from the DX9/DX18 to the DX8 is also supported. RCGRoups thread about the tool is here: