well guess I should make my irrelevant and nerdy contribution to the community.
I have worked out (and could be wrong) the probability of success when attacking an opponent:
No. Att V No.Def
3 against 1 --> 65% chance of winning
2 against 1 -->57%
1 against 1 --> 42%
1 against 2 --> 25%
3 against 2 (Both win) --> 22%
3 against 2 (win none) --> 15% (although i reckon it is about 80% for me)
3 against 2 (win first) --> 47%
3 against 2 (win second) --> 60%
well, there you go