It's just a software update and you can easily install it on all the newer (2005 and 2011, plus remakes) Freezer versions.
Crossing fingers for the multi-saving slot firmware will be available in next batch.
But I'm in contact with Sven and we will make sure that the newly produced Freezers ship with the latest available software/firmware version.
I found a bit of spare time this weekend and fixed a minor bug in the cart preset editor. The (not yet documented) shift-insert keycombo now properly recalls the latest loaded or entered slot description so you can easily copy settings and descriptions from one preset entry to another one - or create another entry with different settings (eg MAC/65 and MAC/65 with SDX) without having to type in the full description again.