I own the SF Auditor M and have been auditioning the M30.1/2. Unfortunately, they are much more similar than I would have thought. After the trial, I thought for sure I would swap, but a day later, I was happy to keep the SF. Both disappeared very well. The SF are a touch warmer and the Harbeths have a bit more drive, which is what I wanted but it’s not worth the swap once I put on some slow blues. I don’t think you could go wrong, but I just don’t want or feel the need to try anything else. I run a VAC integrated and a REL sub in a 12 x 15 room.