Debian has a policy that should be followed about not using conveniece copies of code. There are many packages providing LADSPA plugins that can enhance LMMS. https://packages.debian.org/sid/ladspa-plugin
In my humble opinion, the goal should not be to render projects the same in different environments. This is the same problem with MIDI songs without distributing the samples. The goal should be that the demo songs sound good everywhere, to entice the users into composing new songs, and to provide the best tools available. I believe that using CAPS 0.9 is a better user experience than using CAPS 0.4. I have listened three "cool songs" without LADSPA effects and they still sound cool. If LMMS developers want to provide a standardized set of sound effects, they should take care of this set. They should stick with CAPS 0.4.x in a separate library and provide a how-to to manually upgrade old projects (uncompress and replace strings); you cannot easily distinguish projects using 0.4 from ones using 0.9. These separate libraries should be installed in /usr/lib/<arch-triplet>/ladspa. I could help writing an upgrade_*() method to automatically upgrade projects, but this should be discussed with upstream.
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