2,2mm and 1,5mm cable have both the same speed, there is no difference. I did personally an test installation in the house of a friend in Switzerland with 1,5mm to experience the forces. It was no problem but it helped a lot to use some "soap" when pulling the cable through the conduit. And as you wrote, 2,2mm is more robust. The core of the cable is the same. ( please consider that access to the electrical installation is official only for experts ).
Another difference is, that the 1,5mm cable is lighting when the cable is bended (see attached photo) due to the thin jacketing. Some of our customer love to have this effect some others don't.