The iFilter itself would only generally need to be installed on a crawl server, but the icon and updated xml file should go on all servers.
If in the future the option was added to use AutoSPInstaller to install the Foxit PDF iFilter - that is licensed per-server, so it would only be installed where specifically required.
(Agreed that for the free Adobe one, the split install is just a nice-to-have)
If in the future the option was added to use AutoSPInstaller to install the Foxit PDF iFilter - that is licensed per-server, so it would only be installed where specifically required.
(Agreed that for the free Adobe one, the split install is just a nice-to-have)