A quick update on my experience with SVS Micro 300 and Harbeth m30.1.
A beautiful pairing. Like they’re made for each other. The sub simply fills in the bottom range of most music. The SVS phone app makes all the difference; I would not consider a sub without a remote app now. I find myself changing volume by recording; the sub extends the range if there’s anything "down there". Could be subtle or dramatic - my choice based upon recording. But the extension is always appreciated. Makes the Harbeths into a full range setup. The app gives me almost real time control of volume, low pass filter, and other settings.
The sub itself seems fast and I notice no timing issues. Integration was not brain surgery either. Just not hard with the app and some basic knowledge.
If you’re on the fence, just do it. My guess is you’ll be very happy.