Hardly seems more efficient than off-lining the files in Nuendo, which saves each RX process as an offline process, which you can easily, and instantly, go back to and tweak, then go back again to a different process and tweak, deactivate, etc.
I think that's well phrased and I certainly see the point in it. The only issue with it is that they took out Spectral Repair of the offline plug-in suite and it is now only accessible in the standalone app. When I spoke with support he promised to keep lobbying for bringing it back.
There is however the other way of looking at it which is that if one gets fast at working in the standalone app then all the tools are available right there. For the workflow you describe above you'd have to open and apply each process you'd need for each piece of audio. So if an event requires for example first a pass of DeNoising, then DeClicking, then a hint of DeReverb, a pass of Ambience Match, and a final DeNoising, then you'd be looking at opening 5 plugins. Granted, you'd have the offline history available, but when it's not needed I'm willing to bet it's a slower workflow than just doing all that in RX.
I'll keep tweaking my workflow this week on a short I'm mixing, but intuitively it seems that the issue hinges upon what type of content your working on. A 30-60 second commercial with only VO and a few dialog lines could probably be done faster in RX than offline in Nuendo. On the other hand I can see how some types of programming with more varying sources where we'd need to make decisions later about which source to denoise how much etc will make "locking" one's processed files in RX a bit of a potential issue.
I understand that perhaps for simple NR, doubling your tracks to maintain the original files while working in RX is acceptable, and that you'd probably have little need for an actual process history. But I think Steinberg has the lock on the workflow still.
I double the tracks in both Nuendo and PT anyway. The imported omf/aaf lives untouched somewhere, always. In PT I do a first pass edit on a new set of playlists, right on the omf/aaf tracks (it's just faster for me that way) after which I transfer that to my template tracks. Then before I do anything I do new playlist for those template tracks. I just love having that "safety". So for me it's really no difference from that standpoint.
I think Steinberg would have the lock on workflow if only they allowed offline plugin windows to remain open until I - the user - decide to close them; all while retaining control over the rest of Nuendo. In PT, during my first pass, I leave the RX DeClick open at the corner of the screen and then fly through the first edit pass, quickly hitting "process" whenever I encounter a click. It's super fast and better than having to wait for the plug to open every single time. I think if Steinberg addressed this we'd have the best of all worlds; what I just described, what you just described, and what is done in PT.