+1 karlfife - think you've expressed the 'C' grip advantage very well.
Exactly my own experience.
Yes - if you stand in free air, and wave the two different types around, the pistol grip is far superior in balance.
But..when using the 'C' grip - it's somehow easier to line up, and apply the necessary force - seems more natural.
That's why I prefer for confined spaces as well.
And, imho, does reduce 'strain' on the wrist - which I find advantageous the older my wrists become
Use other makes of drills for heavier work, eg sds hammering.