TheParadiseTrio,

Tough call. If you work with 80% Registrations and want a back-up a regular X1 will do. I say this because the Registrations are NOT transferable b/w the X1, XD9, SD1 or Midijay, so if it is for real back up purposes, I would say another X1.
However, if you won't mind moving up, an SD1Plus would be the best way to go ... if you do not mind re-programming the Registrations on the SD1Plus as well. Now if you want to add the vast and great capability of AUDIO manipulation, MIDIJAY would be worth the wait!!

Thanks,

AJ