Kegetys' Object Files addon adds support for numerous new objects that OFP mission makers can incorporate into missions they're designing. The Object Files addon consists of two files: OBJECTS1.PBO and OBJECTS2.PBO.
However, according to Kegetys himself, Gunslinger's Editor Update is superior to his own Object Files addon, as the Editor Update includes everything and more than the Object Files addon.
Furthermore, Kegetys notes that for players using OFP version 1.30 or below, the Object Files addon can potentially cause errors, as it can override OFP's internal configuration settings in those earlier OFP versions.
Based on the above, here's my advice regarding Kegetys' Object Files addon:
For mission makers, there is no reason to use Kegetys' Object Files addon anymore. Use Gunslinger's Editor Update instead. Even Kegetys says so!
For players that have OFP version 1.30 or lower installed, drop this addon like a hot potato. It may mean that you won't be able to play some user made mission but that's better than the Object Files addons potentially interfering with OFP's gameplay. For players running OFP version 1.40 or above, it's generally safe to use the Object Files addon. If you download any new missions that still make use of Kegety's Object Files addon, consider contacting the mission maker and pointing this FAQ item out to them.