Let's call the difficulty of pressing a key lg(D/W + 1) where D is the distance of your finger from the target key and W is the size of the target key (Fitts's Law).
So if we're talking strictly about a one handed keyboard setup, CTRL is not a good modifier because
- if you use your thumb, it's a difficult key to hit because you have to cross under your entire palm, which will have the side effect of moving your index finger away from 4-5-6, making them harder to hit as well.
- if you use your pinky, shift is closer to resting position and larger than ctrl, and will be easier to press. With shift, the remaining fingers will not have to reach as far to hit their assigned keys.
If we allow a two handed setup, the right hand over the arrow keys places the thumb over right control for PTT; index finger on shift and in range of left arrow, ins, del; and pinky on num0 for quick interaction with mechanical objects. Having movement bound to both QWES and arrow keys will mean that if one hand is busy doing complex chords and scales, the other hand will quickly be able to execute dodges.
A bit of chord complexity isn't something to avoid if it reduces the distance your fingers need to move. alt-shift-3 is easier to hit than 7 any day, especially when those three keys just happen to be the resting positions for the three fingers involved.
Something I forgot to mention in my earlier post...set your two Face Target binds to something simple for each hand, like [`] and [\] so you can keep your target in front of you without having to wait for the GCD.