One thing to think about.
It is possible to run a hot enough brushed motor to NOT be fast on alot of tracks....
Therefore, as far as brushless out-performing brushed- In many applications, we have the batt power to run such hot brushed motors that it is really overkill.
With the new long run (xxx lemans costing about $7 most places) I think brushed motors are still very economical. And for the backyard basher or novice racer, a standard speedo can be had for reletively cheaply, whereas brushless speedos are spendy.