FWIW....
I religiously use both brakes on the street (as practice for that panic stop I'm gonna' have to make). Just good habit.
At very low speed (parking lot, and full lock maneuvers) I use rear only.
Sometimes to just scrub some wee speed, I'll feather the rear. I like the C14 not so powerful rear brake.
On track on my supermoto...
I can back it in quite nicely w/out rear brake. I've recently taken to riding it more with no rear brake under hard braking, so I tend to brake more (and harder) with the front, since the rear is sticking a little more. I noticed with less front brake action, and more rear applied, the bike wanted to get way more sideways and was less controllable. Worse if I added more front brake. On the same bike I would ride the same corner, no rear, and could actually slow harder/faster, and keep the rear more under control.
I'm gonna' have to work more on no rear brake on the track.
On my TTR125 indoor bike, I can rotate the dog **** out of it, and the rear helps a lot as there is no slipper in that bike, and I get chatter out of the rear if I hamfist the clutch. Application of rear brake seems to lessen than.
YMMV,
Barry