Regarding the timing, I'd say from our experience working with team driver, and customer racers, the timing has very little effect on the laptime.
We've turned it "all the way up" and "all the way down". Basically what you do is change the gear you can run, but not the speed. We don't talk about the timing much, because it really is a non-issue.
This has been confirmed by many oval racers, and onroad racers alike. Fast guys that win races as well as your average joe "C" mainers. I myself have monkied with timing only to find the same thing our engineers told me would happen. Turn the timing all the way up, you end up gearing down, turn it all the way down, and it will need more gear.
Brushless motors timing is not as effective as a Brushed motor timing I think.
I don't think even the slowest brushless motor will ever be equal to a Brushed motor. It's kind of like real cars. A carberator, and a Fuel Injection system "do the same thing", but a fule injection system has abviouse inherient advantages.
The combining of the two types is only an effort to stop one from becoming "obsolete". Once you get a "brushless" class running, many racers will shy away as they feel they "have to" run BL. If you leave it open, the "Super Stock Tuners" can stay competitive and race and tune their hearts away.
I think the big difference is with the 13.5 is that you get a pro built Stock motor out of the box. I've been racing for a long time, it takes effort, time, and a lot of know how to get the most out of a good 27 turn stocker. It's a lot more then just cutting the com, changing the springs and brushes. WIth the 13.5 it's like getting all that "done" just buy opening the box and bolting it in. So yea, the guys who struggle in stock will for sure go faster, cause these guys never spent the hours on their motor to make the "jonny fast".
Adding the sintered rotor to the 13.5 ups performance even more.
We're always here for emailing and tech calls if anyone needs.