What's even more confusing is that there's two models being sold in SA with no mention of it in the product listings.
The info that I had at the time I purchased my grey TPE are that, we have the TPE's which are the 609 model with the smaller backrest and the other variations are 709 with the larger backrest. The importer is
Home | office-furniture which is ODO's supplier including ITOfurniture (there are fakes out there too, original has 3 year warranty not 5 years).
I prefer the 609 backrest but my experiences are the same as Firestorms... initially I hated it. I was under the impression that the TPE seat warms up and molds to your ass but that's not true. It's literally hard plastic, not the same composition as the TPE on the backrest and headrest which is more softer. I've gotten used to it now and its definitely comfortable after the initial phase but occasionally I still get a pain at the base of my spine.
I initially ordered from ODO with foam and mesh (709) and I also felt the foam seat giving me the same pain but returned it due to an out of the box scratch on the armrest and difficulty with the lumbar adjustment. The foam seat is very high density and I found it to be a bit hard. Adjusting your chair to the correct height makes a massive difference to the pressure on your spine and ass.
I then ordered the TPE from Adel (she's awesome) at ITOfurniture after testing them all out at deskandchair. What sold me on the TPE was the backrest shape (609), comfort during the short period I sat on it and the fact that all of the sales people at deskandchair were using the Wau TPE's!
(You can see their desks from the showroom)
When I tested the mesh seat (709) I found that it has the most, "give" so you sink in much more in comparison to the foam and TPE.
I also have a few ticking or clicking sounds from the base mechanism after returning to the standard position from reclining. It quite audible but doesn't bother me that much since I hardly recline. It has a 3 year warranty so I might lodge a warranty claim in future.
I know that's a chunk of text but hopefully that helps any of you that are planning on buying one.