[Slalom4me]

I'd be interested in how these might be handled without adding knobs all over the controller. 
One of my pet hates with the slot.IT SCP is the rotary knobs that are hard to tune, easy to knock out of adjustment and impossible to adjust by touch only.

Hmmm.  So, you dislike analog rotary knobs. What would you propose as an alternate?

Please do not say an LCD with a narrow-field-of-view display, inadequate brightness and buggy touchscreen response hosting a complex multi-layer menu for access to basic control parameter settings running on a sluggish operating system.  (You know, like the center consoles now provided in modern vehicles, in place of radios and heaters operated by knobs, buttons and slide controls.)

I have an SCP-2.  The knobs have sufficient resistance to movement that I have not experienced a change in setting from inadvertent contact (and the controller is carried mixed in where it can bump against other stuff in the pit box.)

If what Nonfractal means by "impossible to adjust by touch only" is that there are no detents providing tactile sensation of distance travelled during a rotation movement, he is correct.  Within their range of movement, the knobs are infinitely adjustable.  In practice, this works for me. 

Detents are fine where knobs are large and the amount of change per unit of rotation (sensitivity) is low.  When knobs are small and sensitivity is high, then often as not, I discover that the exact spot I want to position a knob is smack dab in the center of the high spot between detents.

As for having to glance at the knob, what I find is that I adjust controls while underway, tuning each in the moment in response to how the car is reacting.  Not caring about where the knob is set physically - unless it has reached the end of its travel.  Since cars vary in their response to control settings and my memory isn`t what it used to be, I customarily make a note of where knob settings wound up following an on-track session with each car.  The next time that car goes on track, a quick glance at the notes tells me where to set the knobs for a baseline to start the new session.  Keep in mind that settings are not just related to the cars - when the operator is sharp, tuning can be moved towards the pointier end of the spectrum than it can when when the operator is off game for whatever reason.  It is not uncommon for knob positions to change during a session, even with a very familiar car.

In closing, the SCP-2 offers control over some, but not all four braking parameters mentioned earlier.