Did you read the review? If not, let me point you directly here:
Sirui T-025x Travel Tripod Review - Overall Tripod Stability - PentaxForums.com
That's a stability test at macro magnifications using a laser pointer.
and
Sirui T-025x Travel Tripod Review - Real World Usage - PentaxForums.com
That will have images taken with the tripod, some super long exposures that resulted in tack sharp images (30 seconds long a few of them!)
The T-1205x is a bit bigger, and naturally a bit more stable, but for me, I choose the T-025x because it's smaller, and if I really need stability, I hang my camera bag underneath it using the camera bag hook under the center column. ROCK solid then.
I can't speak about the T-1205x, but my experience has been 100% satisfied with the T-025x. In fact, unless I'm using super tele photo or am shooting in my (very very small) studio at home, I
only bring the T-025x. The bigger tripod is left at home 100% of the time now. You have to decide which compromise you are happier with - a bit more stability, or compactness? The latter you can't change no matter what you do, but with some minor tweaking (i.e. hanging something from the weight hook), you can add stability. At least that's my philosophy. Your priorities might be different.
-Heie