>The number of times I've had issues with CDX files going bad can be counted on one hand. In fact, my experience is that almost all corruption of tables or indexes boils down to failure to have a UPS or network trouble.

There is an issue with CDX files bloat when you have "circular" tables (tables where you keep the same number of records and you start overwriting when you get past this number, for example you want to have 500,000 records, so when you've got to write 500,001 you overwrite record 1) after a while you need to reindex for the CDX file size keeps growing and it either starts failing or you get to the 2 Gb limit.