Guess I will add my 2c worth from an audiophile point of view.
I had the Elac Navis in my system directly fed from an SMSL M500 ii DAC. Direct & simple. Sounded great.
My main issue is integrating with OB subs, crossing around 65hz, I use 2 pairs of UM18s in clamshell arrangement driven by NX6000D. This bass arrangement gives me everything I want with minimal room artefacts. Its the tops I have trouble with....and to date, the Navis were the best I heard in my system. I have learned it is essential to have a HPF, especially with reflex which tends to bloat the midrange and react with the room.
However, when I viewed a review on YouTube where the Navis was compared to the Focal Shape 65, this piqued my interest, and brought me to this thread....a bit late....but others may be interested as a reference. This speaker is unique being active with twin passive bass radiators.
To cut a long story short, I bought the 40's to try, then the 50's, and have not looked back. The 50's do everything the Navis do, but better. More open mids.....perhaps because of better bass control from the PBR's. As one reviewer describes, they are more up front in a neutral way. More dynamic and engaging. They are also half the price!
I have not found the PBR's to be slow or ploddy at all. The opposite, in fact, where the bass slams & punches, always with tight control & timing. It is also full of detail, texture & timbre, and does not obstruct the mids.
Before the Shapes I tested the Kali In-5. It looked like a Navis clone. I sent it straight back. It was awful with a boomy bass and veiled presentation. I felt no amount of run-in would fix that.
For the type of music I listen to, the 50's have more weight than the 40's in the upper bass, but the 40's may have clearer mids....could be because less bass. Doesnt really bother me as the 50's are clean enough. They also go louder.
You may have noticed I fitted an 80mm fan to the back. Not sure it was necessary, but it keeps the back plate 10 degrees cooler and fits onto the M6 bracket retainers in the rear.
Shots of Shape 40 internals: