You're going to get roughly the same CFM out of both of them. There may be a minor difference, but not enough that it's noticable.
I personally choose L1A's over Silencers because the L1A's use a hydrowave bearing, whereas the Silencers use a traditional ball-bearing. Hydrowave bearings are generally more reliable and slightly quieter, mainly because they never need to be lubricated. So yeah, L1A's are the way to go, if you ask me.