tintin,
You should do what you feel safe doing. Inexperienced riders probably should not lane split. Certainly those that feel uncomfortable or incompetent doing so should not. But, I've known several different riders, waiting, stopped in a normal cars position in traffic get rear ended by cars that failed to stop. I don't wish to be presented as this type of target. When I do wait in line with cars, you can bet my bike is pointed between cars for my "out" and I watch my mirrors for vehicles behind me.
I find it much safer to ride where cars are not moving in close poximity. 10-20 percent of the 40-80 parked cars passed in traffic ARE trying to kill you. Some by intent, some by virtue of the fact that, although they are in the drivers seat, they are really just casual passengers occupying a part-time guided, lethal, weapon, more involved with; food, make-up, cell phone, newspaper, magazine, radio buttons/dials, and yes, TV. (Yes, I've noticed ALL of that while lane splitting.)
The more cars I can eliminate as threats along my route, the greater my chances of survival.
Lane splitting safely does require skill, alertness, and even courtesy, the later of which is rarely seen on the streets. (I do try to re-introduce these concepts when the opportunity presents.)
Can lane splitting be unsafe? Absolutely, I see it done that way occasionally. (I see far more of other, more dangerous, infractions.) Is it inherently unsafe, no. Further, it helps to reduce traffic congestion.