That's funny, I hadn't noticed where you were from, just decided to say thanks in French for some reason

Can I just ask what you were referring to when you said "I think this could considerably speed up NPC vs NPC rolls and the likes, and I'll probably start using it for that."? Were you refering to the LowDie system or something else?
In terms of probabilities - the LowDie probabilities are all in the Appendix of the system, and I would imagine that someone has the same for Shadowrun.
As an example I will start...
LowDie - A person with an average Attribute Total of 10 makes a test with an Average difficulty (DN of 6). The chance of Success is 85%, made up of:
06% Incomplete
24% Adequate
27% Good
18% Excellent
10% Outstanding
Shadowrun - A person with an average Attribute (rating 3) makes a test with an Average difficulty (TN 4???). The chance of success is 87.5%, made up of:
37.5% 1 success
37.5% 2 successes
12.5% 3 successes
What you decide a LowDie Success Level is equivalent to in terms of SR successes is debateable, e.g. an Incomplete + Adequate success could be considered the equivalent of 1 Success.
Anyone want to do the rest?