Thx for your advice Trent,
I forgot to mention that I actually have done what you proposed for the most times of my practice, namely 1/2 hour samatha, 1/2 insight.
That´s what I thought it was at the time, though I know see that I indeed used the pure unfocused or soft part of vipassana.
I had a really great session this morning when I tried to incorporate all of this. I maintained focus on the breath during the first half hour basically persistently with only short flows of thought/distraction but without losing focus on the object entirely. This really helped in penetrating the sensations in the 2nd half. I started with my left hand for up to about 10 minutes trying to feel the sensations of it and what those themselves consisted of. I managed to get into some kind of tingling sensation but couldn´t go any further yet.
I continued this procedure with some back pain which eventually resolved after some time. The next pain I approached was in the neck area but that nasty little thing resisted all my efforts for about 20 minutes. ;)
While doing this I recognized being quite motivated and enthusiastic about the maintained focus that I achieved, so I feel like I´m on a good track on bashing impermanence permanently.

Anyway I have some other experience that I can´t quite put in place yet.
This doesn´t happen while doing sitting meditation but when lying down (which i used to do in combination with holosync and lucid dreaming practice):
After some time of relaxing the body while maintaing awareness Id get serious vibrations foremost in one or both legs.
I wonder if these correspond to the mentioned vibrations felt in A&P?
However these tend to get so intense that I just have to stop the practice and I haven´t meditated lying down since.
Is it possible that my body isn´t relaxed enough while sitting that prevents those vibrations from appearing?
Really appreciate the feedback!
Martin