Ok, after all my laughing and "I'm telling you"... I think I must concede to Darkas

... boy I hate being wrong.
I also asked myself:
If someone bet me 500 dollars that I could not flip heads once over 5 coin tosses, I'd take them up on it, betting that I could
If they asked me to do this over one coin toss, I would decline, as my odds are definitely 50/50.
Obviously, as Lopdo first pointed out, the more tosses you have to hit it just once, the better your odds. And as Darkas has stated, it does only take one win as an attacker to win the battle.
So, the odds of winning one over many does logically appear to increase, while the odds of winning each one does not. That said, the formula used still did not makes sense to me in a practical sense what-so ever, as I surely do not expereince this type of result using the boosts with equals... I still lose more often than not on both rolls. However, assuming a 47% win on one roll and being an attacker, in order to lose with a bonus, the math is in fact:
.53 x .53 = 28%, and hence the attacker is 72% likely to win on the FIRST roll, and 47% likely to win on the second, if the first roll was lost. The value does change based on the number of roles you have left. This makes me want to attack equals more with boosts, however, I have such awful luck attacking -1 properties (properties with 1 man less than mine), that I use my bonus attacks mostly on the first turn to assure I win 4s over 3s, and 3s over 2s to connect up and build strong from the start. So 1/2 my boosts are wasted to assure a strong start and win, and hence considering usage, does degrade the overall % gain in men killed by using them.
For those interested in a good reference on Darkar's math:
http://en.wikipedia.org/wiki/Gambler%27 ... _fair_coin