Don't move the DLL or it will cause problems with incremental upgrades. SD2 needs to be upgraded from 2.0 to 2.3.2 anyway.
Either include or add the path to the DLL in the REAPER plugin path in Prefs, or uninstall SD2 and reinstall it with the DLL path where you would like it.
With the former you may have to "clear cache and rescan" to get REAPER to pick it up. With the latter, you can do this without erasing your sound files, the bit that takes all the time copying data from the DVDs.
Hope this helps and the OP hasn't forgotten about this post
Edit: I run a test copy of SD2 on a laptop with the libraries on a USB drive and it works ok. program files and DLL on the OS drive, but libraries on external drive.
It might take a little longer to load a library up, but Superior and EZD load samples to RAM where they are run from, so no playback bottlenecks.
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