Restoring ontape archives between 32 bit and 64 bit versions of Informix

Unfortunately I don't have the equipment to test this on which would be fairly trivial so I am asking this here. We have a customer who has two 64 bit AIX systems running a 32 bit kernel and a 32 bit version of IDS. The two servers are replicated via HDR. They also have two older systems running AIX which are backups servers and also serve as a test suite. These are only 32 bit capable. The data is transferred from the main system to the backup system using an ontape archive. At the moment everthing runs the same version of IDS so all is OK. Am I going to have problems with the ontape transfer if the main system runs IDS 9.40.FC5 and the the standby server runs 9.40.UC5? My hunch is that this isn't going to work. On a related note, and sorry if this is a "how long is a piece of string" type question, what sort of performance improvement can I expect by moving to a 64 bit kernel running a 64 bit version of IDS over 32 bit versions on the same hardware? Ben.