These grand conspiracy theories sound great on paper. But then, when I look at what happened on the ground, I get a reality-check. How the hell are Mossad agents supposed to kill Hariri in the middle of $^#^&$ downtown Beirut without anyone knowing??? Taking into consideration the size and complexity of the operation - for God's sake it wasn't a sniper shooting - the likelihood that someone carried it out without getting the attention of the security services is virtually null.
Seriously, how the hell are you supposed to get 500-1000 kgs of TNT without anyone knowing? Did Israeli commandos bring it with them by boat? If so, then how big would the boat have been? Assuming they somewhow managed to do so, then how could they plant it underground without anyone noticing?
As for this whole hegemony thing... it is also kind of a shaky argument. Egypt and Saudi Arabia are definitely not militarily up to par with Israel, but they do have their weight, and can influence events in the region. Even Jordan was able to get weapons from the United States that Israel thought were too threatening, and tried really hard to prevent from happening. So these theorists do two things: they play on an inert fear of Israel, and completely ignore facts on the ground to make what would seem to be sound arguments.
In conclusion, I'll say the following:
1. The Syrians have no problem killing Lebanese (or anybody) who they perceive as a threat to their grip on power.
2. There is a huge difference between American hegemony (a reality that we are dealing with today) and Israeli hegemony (nonsense, considering Egypt, Saudi Arabia and even Turkey - all of which are allies of the USA).
3. Read the following article from Dier Speigel: