[nicky g]

You're veering into the morality of such actions again when I was simply asking Tom if he really beleives whether this would escalate the conflict or not.
But to anwer your questions, I do think there is a difference in the two situations. Bin Laden is already an acknowledged target. The conflict between AQ and the US has seen the WTC attacks, the invasion of countries etc; it is significantly more "escalated" than the conflict between Israel and Hamas. Furthermore bin Laden is the acknowledged leader of a paramilitary outfit. He does not claim anything else. Yassin claimed to be and was seen by many, whether you agree with them or not (and I'm sure you don't) as the spiritual leader of a religious-social movement (Hamas) with a paramilitary off-shoot (Izzedine al-Qassam Brigades). Bin Laden has boasted of his involvement in planning attacks; Yassin denied he gave them anything other than his approval. Bin Laden is hding in the remotest place on earth; Yassin lived openly at his house in Gaza. Whether you see it or not, most people including the Israeli government up until recently, saw a clear difference between their status as "targets".
On the related point of whether I think killing bin Laden would make much of a practical difference to the fight against al-Qaeda? No, not really, except in morale terms. Yassin can be replaced; bin Laden doesn't really need to be. Most of "al Qaeda" consists of local groups who have zero contact with people hiding in Afghan mountains.