Can't wait for mine to arrive.....was about to pull the trigger on IIIs, but they were out of production so I put deposit on IVs....
I bought the Forte IIIs a month ago, and they are amazing speakers in my multi-use room (35 ft x 18 ft). I have them powered by Classé CP-800 and CA-2100 combo ... magical and very musical. My music collection has never sounded so good, period! Last night I saw the Audio Advice YouTube video on the Forte IVs and decided to contact my dealer to see if they would do an exchange given how recently I got the IIIs. They agreed and now I have a pair of the IVs on order. Music already sounds very real and live with the IIIs and I’m expecting the IVs to be even better. I’m really looking forward to it.
No kidding.  Good dealer and almost perfect timing (you got the use of the III for a month plus your wait time for the IV's).
As a current owner of Forte IIIs, I'd be curious about crossover improvements in the IVs. 

I've considered the Forte III upgrade kit from GR Research, it includes upgraded crossover, bracing and damping. 

The crossovers requiring soldering, however, which is not a skill i possess.