Update after 10 weeks of wearing:

First of all, I have been very satisfied with the results. So far I feel like I made the right decision. I have been able to live my life, go to work et cetera - without spending all the time in front of mirror worrying and trying to somehow style my existing hair. I was really desperate and depressed before I started wearing, so in this sense I'm very happy.

Some facts:
-the system itself is a very small partial, about a 1-2 centimeters wide, going from temple to temple
-I deattach/reattach every third week, and wash the piece at the same time
-I did the cut-in myself, and also have modified the system a bit myself by cutting the lace
-I have been living my life as before, going to gym a lot, running etc.

Some things which I'm not so happy about:
-I still sometimes worry about getting busted, and feel that I'm somehow "fake" or something like that. And I don't feel comfortable to reveal the fact that I wear to anyone
-The shape of the template I ordered. The hairline is a bit too much forward. The next step for me would be to shave a bit of my existing hair, and create a template that is more realistic when considering my head shape
-The time it takes for me to deattach/reattach. I need about 6-8 hours to do the trick, including detaching, shampooing, letting the system dry, gluing it back on etc. (I guess there are ways to speed this process).

All in all, I am very happy about the results. There are still some things I need to learn, and some things in my routine I need to improve. But it really has been worth it so far. I want to thank John and everyone in this forum for giving me the confidence to take a step forward.