Because my lathe's motor is not very robust (That's what I get for
opting for the $200 H.F. cheapie), when I'm roughing larger bowls, it
stalls very easily at lower speeds. But, the lathe is dancing around
from the wood being out of round. I've noticed that a higher speed
gives a better centrifugal momentum (and faster cutting as a result),
but increases the risk of the blank flying off. This is especially
true because I usually initially rough between centers. Well, actually
the greater speed doesn't increase the chance of it flying off, but it
certainly affects at what force it flies off at!

Anywhoo - So far I've been hit in the belly/chest twice now by a 5-10
pound piece of wood flying out of control. From what I remember, it's
because I had the speed too high and I was standing in the wrong spot.
Me standing wherever doesn't affect the wood comming off, but it
certain affects how *I* end up. I suppose the cutting tool was to
"blame" as well (always the worker blaming his tools), since it caught
the piece good enough to throw the wood off center.

On body stance, there still is a chance that even if you've out of the
way, a piece could still hit you. I've had broken pieces bounce off
the wall(s) or other objects and hit me. In this case, usually the
force isn't good enough to cause any bodily damage. I'm positive
anyone reading this already knows all this.

My vote is lower speed for safety purposes. I'd rather take longer to
rough for the sake of being safe. I'm taking this in the context of
medium/large sized bowls. I'm not sure (yet) about spindle/smaller
works.