Onbar Scalability Issues

We are currently running informix 7.24 on Solaris 2.5.1 (E10000 Platform) and have been using onbar to do backups through to Netbackup. This generally works ok, despite the database being 300Gb of used pages in size, although it does fail with connection timeout errors. The connection timeout errors wouldn't be so bad if the connection to Netbackup was remote but in this case it is all on the same machine along with the backup robot. Also when trying to enable additional onbar's to run by specifiying the dbspaces to backup the error 54's get progressively worse to the point where a good daily backup is un-achievable. Does anyone else use onbar in this way i.e. onbar -b -L 0 <dbspace list>, and changing the onconfig to allow multiple onbar's to run (BAR_MAX_BACKUP 6) ?