Anyone listen to Zu Audio's Definition Mk3?

I currently have the Def IIs. I requested and received information from Zu last week on the "Definition Mk III Transform". The work they do is extensive, much more than replacing the 10" drivers. The speaker is totally disassembled. They rematch tweeters, upgrade to a silver/oil Mundorf cap in the hi pass filter, upgrade to the latest hypex amps, all the electronics are replaced with a modular unit with new controls (sounds identical to what's in the Def IV). Additional bracing, damping and reinforcing is done to the cabinet. While I am sure there is a substantial difference between the Def II and Def IV, what I really want to know is the difference between the Def III and the Def IV. If the full Def III Transform gets me to 85% of the Def IV I believe I would be a pretty happy guy for a long time. I am hoping 213Cobra can provide that info.

Is the rear firing bass array replaced with the downward firing sub?

213 is to busy listening to his 4 to write.

I have had my Definition Mk4’s since Dec 20th and I use them with 5 other guys for doing blind testing of cables. We prefer a speaker with no crossover in the vocal range. The Nano driver is very fast and super revealing without be harsh in any way. The sub and sub amp are very well matched. After owning over 300 different speakers in my life I discovered Zu about 2 years ago. I have tested almost all Zu speakers and the Definition Mk4 is the best all around speaker I have owned in 30 years and also one of the least expensive speakers I have owned. If I didn’t like it would have already been up for sale. Make sure your cabling is up to the task and you will be in the recording studio with the artist; a true emotional experience.

As contented owner of Def2s, just a couple of things. Firstly, I've always loved the 'tone dense' sound of the Def2s, even though this is at the expense of best possible treble extension; so is the new Radian tweeter on the Def4s an improvement in this area?
Secondly, the massive bass output of the Def2s have led to room nodes issues, but I've been able to better integrate bass from the speakers into my room using the SpatialComputer Black Hole attenuator. Does the use of the single downward firing sub really improve upon the 4 rear firing drivers of the 2s?
Regards, Marc