upgrade Dynaudio Special 40 to Kef Reference 1

Yes, it is an upgrade.KEF Ref 1 has more defined treble, mids are more detailed and tones are more accurate, bass goes deeper and has more substantial weight.

That said, it is not necessarily better, as the special 40 is less neutral, produces louder bass and slighlty more elevated 100hz which makes it more "satisfying" to some people. A friend of mine did that exact same upgrade although he has a H190 instead. He finds the Ref 1 to be the superior speaker, but still misses the more "fun" (I can't believe I'm saying this for dynes) special 40.

Upgrade Dynaudio?
really?
those two words are oxymorons when used for Dynaudio,   

 Maybe trade in for another Dynaudio pair, KEF , is by no means a slouch,
dynaudio,....are an amazing speaker, etc 

good luck, let your ears be the judge.

I might want to add the Focal Kanta No.1 (lower price) or Sopra No.1 (higher) to your check list before laying down your cash.  The Sopra is a stunningly well integrated, surprisingly wide range, relatively compact stand mount. I haven’t heard the K1, but if the No.2 is any indication, it too deserves a listen. 

For the sake of transparency I should mention we are Focal dealers. But I speak for myself.