Derailleur upgrade for my recumbent

[Ducati]

I have a RANS Tailwind recumbent with an older SRAM 5.0 esp derailleur (1:1 actuation) and SRAM 7.0 esp twist grip shifters. I want to upgrade to a newer derailleur. I understand that the newer SRAM X7's & X9's might not be compatible, so before I go ordering a new derailleur, I should find out as much as I can about what bis compatible and what isn't.

[nfmisso]

up to (and including) 9 speed versions; no problem.

You should definitely replace the cable at the same time as the derailleur.