A few reasons, and my process doesn’t require the RX connect plugin or anything. It’s very fast. I copy of a selected area opens in RX, and RX is focused for you, all in one click.
I like having a visual map of where edits were done on song, which REAPER provides with this workflow. This is especially useful when a client sends a new version of a mix that needs to be redone though the analog gear. I can just replace the mix in my REAPER session, and reprint it as a new take on the capture track. Then in REAPER I can also see where all the RX edits were done, and need to be redone because of the take system it uses.
I’ve even done things like preserve the very tail end after the final downbeat that was already fixed once to remove, noise, metronome bleed etc, assuming the mix didn’t change at the tail end. Then when I render a new version of of REAPER for WaveLab, the new file is EXACTLY the same length, because of regions in REAPER. Or if the beginning of a mix didn’t change, and I did some careful noise reduction, I can preserve that seamlessly and be confident things are in sync instead of manually pasting things together.
The standalone app is maybe a bit faster but you have no map, no easy way to get back to the original audio for a small (or large section). It’s too all or nothing for me.
If I’m working in the WaveLab montage and notice a click, I’d love to just highlight that section, fix it in RX, and have the fixed section be active. My RX workflow just makes a copy of that small section which prevents the original audio from getting overwritten.
In the end I end up with less of a file mess. After I fix up a song in REAPER with RX as external editor, then I render a new file of the song, perfectly named and ready for WaveLab. Also, no audio that didn’t need to go into RX went into RX. Maybe a little OCD but it’s one less process for the majority of the song. Only the bits that needed to go into RX went in.
This saves me from exporting the whole song from REAPER, then fixing in RX (with no map or help as described above), and then into WaveLab. A little too much bouncing around and extra files.
Also, I do this AFTER analog processing but before final processing in WaveLab because if any part of this needs to be redone or undone, it’s a matter of seconds to do.