I have definitive answer from support, that cab presets run at 44,1 kHz and 24 bit. Copying IR with higher sample rates will not create any benefit.
I have a LOT of IR with 44,1 kHz copied and archived in RM - and now I know for sure, I don't have to replace them with IR with higher sample rate.
Thank you for letting me know I'll continue to use 44.1kHz format