Today I noticed something about reading the same geodatabase feature class twice, using multiple feature types within the same reader. FME doesn't do this.
I had one single merged feature type set up, to process all data within the geodatabase. This was the only reader in the workspace. At some point I needed one specific feature class from the geodatabase for a specific function, so I used the "Import feature type" function to do it. From there on, that feature class would no longer be output through the single merged reader, but only through the separate one. Suddenly my workspace was no longer outputting all data from my geodatabase, since the separate feature class was discarded halfway through the workspace. However, there was nothing that indicated that this was going on - looking at the properties of my single merged feature type, it still claimed to read all feature classes. Disabling the separate feature type did not affect the single merged feature type - it still didn't read everything. Is this intended behaviour or a bug?
In my case, this was the ArcObjects reader in FME Desktop 2015.1.