Level 6 is almost always slightly *slower* than level 5.
Bwhahahahahaha 
- L5 or less trainer owner
Ha.
Lest I be misinterpreted, let me make clear that I don't *believe* this result. In fact, the error bars show a pretty big range of possible values, including values where (as we assume the true value is, given our belief in competent, non-malevolent, BB's!) it's slightly faster than level 5. What I'm saying is that *we can't tell* what the real difference is.
But I think it's safe to assume that if we can't tell how much of an advantage it is (or whether it's an advantage at all) with this much data, the effect is likely to be pretty small.