The tripod is a weak part of the system. I had to make a wooden stand for the eyetracker to keep its position stable:

At the same time Tobii's devices have a magnetic plate to mount the eytracker on the monitor. I thought before that it is more useful: 1. you can move your head without affecting the calibration. 2. the eytracker's position is tightly linked to the monitor, you'll never occationally change it.
But...
The problem is their latest EyeX tracker has a poor camera, and you need to position your head close to the eytracker, i.e. the monitor. It is comfortable when you have a small monitor ONLY, e.g 10" tablet. If you have a bigger monitor - you need to sit far enough from it, and the eyetracker on the monitor loses your eyes.
On the other hand you can place TheEyeTribe tracker as close to your eyes as it's needed, no matter how far the monitor is. If you wear glasses it's better to position the eytracker significantly lower and closer than the monitor. And it's only possible with TheEyeTribe design.
If you want to know, I admire TheEyeTribe. Because they had promised a $99 device when Tobii's price was startng at $1000.
However, until now the Tobii's software looked more mature for me.
But what they are shipping now - the EyeX device... is not that good any more. Annoying red lights (cost saving, no IR filter), low working distance (again, cost saving)...
And the new Tobii's SDK... is a madness. What I could write in 10 lines of code now requires hundreds of them.
So, all the best to TheEyeTribe team, and, in general, all the folks who make the life easier (including Tobii).