Haven't really had time for critical listening yet, but in casual listening I am very impressed. The difference in SQ was noticeable immediately especially in transient response. The high end is crystal clear. Bass is very well defined; just very solid. Imaging is improved a bit (although it was very good before).
Basically, I'm just enjoying listening to them so much as we go about our routine that I haven't had time to really do some critical comparisons. We live in a 1500 sq. ft (140 sq. meters) loft style apartment and the speakers are in the living room/dining room/kitchen. So whatever anyone listens to, everyone else pretty much listens to the same thing. The room is very large in volume. Say 20' x 33' with 11 foot ceilings (~200 cubic meters).
There are a lot of variables that have changed so I need to experiment a bit. My previous setup was a Sonos Connect directly connected to non-SL DSP5200s. Now I have the Sonos Connect feeding the 818v2 as well as the MD600 with the speakers upgraded to 5200SEs. So I lot has changed. In addition, I am adding Hi-Res files to my library which wasn't possible with a Sonos only system. That said, I suspect most of the improvement is due to the speakers.
BTW, I really appreciate this forum and this community. I would not have made these purchases if I hadn't found this forum and learned so much by reading older (and current posts). So thank you all!