I have a '17 6mt and I've noticed that when the clutch is engaged, the throttle pedal does not work when the brake pedal is depressed at the same time. I realize that it sounds like you would never do this anyway, but I still don't like that the car is not allowing me full control. That's the whole point of wanting manual to begin with. This is the first of 12 cars I've owned that does this.
I wonder if it is the same thing with DSG. You said you were riding the brake pedal due to fear of climbing too quickly. I bet that your throttle is being cut electronically with the brake applied, just like mine is. Frustrating. I'd bet it's a "safety" feature designed to guard against people that don't know how to drive. It's hindering mindful techniques that have worked for years, thereby enabling people to become worse drivers.
The good thing is that when the clutch is disengaged, the throttle and brake can be applied at the same time (necessary for heel-toe downshifting).