I have a tekdesk 2.0, which I ended up finishing a custom top for last week and put it into service over the weekend. With the special on the frame, and the material cost of the desk top it came to around R9k. I used a solid wood Saligna laminate and finished it myself, so basically tools/time. The resultant desk is very heavy (around 50KG), as the dual motor frame is built solidly and weighs a lot.
A few notes:
The dual motors have no problem with the weight (including all my junk on top of it) and moves very quickly.
I'm 191cm tall, and I find around 117mm extension works for me (125mm is max).
My monitors are both on arms, and as you've read there's a shake. When in the seated position this is barely noticeable, and in my case, making the monitors touch reduces any shake significantly. At full extension the legs act as very long levers, so any movement on the desktop (lots of weight up top) and play in the legs is amplified. The desk surface wobbles, and so do the monitor arms; I find it really annoying and have to make sure to avoid typing too hard.
My cable job is still unfinished, as I'm still deciding where to put my case. Cable length can be a major issue if you want to put the case on the floor. The frame takes up a lot of space under the desk, so mounting it underneath has a few challenges.
You will probably need something for your feet if you have hard floors (mine are tiled).
Is it worth the pretty hefty price? I don't know yet, but I do really enjoy having the option of standing. I don't think it's worth the R15k price tag on some of their options.