I think the real question is: When will BL 13.5 and 10.5 spec classes make the stock and 19T brushed classes extinct? Unfortunately, I don't think that will happen for at least another 3 - 5 years, but I really don't care because I only race mod. Thank God!
At my local track, the race director recently allowed Novak 13.5's in stock. That made lots of people happy and it made one driver's parents very unhappy. You can't always please everyone so my advice to the race directors would be to please as many people as possible. If your track has a message board, put up a poll about this topic and let the majority rule!
BTW, I've seen the Novak 13.5 BL with sintered rotor up against good brushed stock motors and I'd say the BL has an advantage, but only towards the end of a race. Kind of like lipo...