dbexport/dbimport tape fault?

I have heard that there is a curious "feature" with regards to the Informix dbexport/dbimport utilities. When using the -s tapesize option you give the KB size of your tape. However, if this should resolve to a number of bytes which is larger than an unsigned int (dbexport) or signed int (dbimport), the utility will use an "undefined" byte count. Also, if one wishes to restore a large database, better to use the signed int value. The actual integer maximiums will vary according to machine architecture , the fault may not be present on some Informix machine implementations. I believe that it is present on the IBM RS9000 AIX machines. The fault has reportedly been fixed on Informix version 7. I know of a case where a site with a very large DB started to use a 5GB 8mm tape backup. This fault, however, means that only part of the tape be used. Is this the case? Can anyone shed any further light?