upgrade path from my current speakers? (Dynaudio Special Forty)

+1 @soix 

Indeed, OP, you're really at a choice point -- finding out whether you are really interested/able to improve the *sound* or whether you're actually more interested in swapping gear. A lot of us have thought we were after better sound when in fact we really had Gear Acquisition Syndrome.

Given all the speakers you have tried, and how much you like the Dynaudio's I would suggest speaking to a Dynaudio vendor and ask them which speakers up the line would carry forward and improve on the characteristics of the Special 40's. 

Others have mentioned the rest of your gear and I agree you might want to consider some upgrades. You could make some big improvements without spending a bundle.

As an aside, I am considering a speaker upgrade from my LS50's, and Dynaudio is on my list. Any comment on the difference between these two?

I agree with the sub suggestion.  Lots of used subs on the market.  Do 2 as they are easier to integrate. 

Re: Dynaudio; My at home experience was Contour 20 was a significant bass response upgrade from Special Forty.  Plus you don't lose the excellent natural vocal soundstage. 

Also add:  The resale market for your Special Forty's is very strong.  I'd reach out to some of the retail resale vendors as well as posting.  If you have original box and materials you may get near what you paid for them.