The idea behind the C260 clamp is that the faceplate needs less clamp force. Thus weight could be saved with lighter hardware that won't require as much torque. Going Torx is logical, since it lower the chances to round out the inside of the head. I don't understand why Ritchey didn't go that route from launch.
Tom Ritchey himself explains it in this video: https://www.youtube.com/watch?v=C1B-58LKNS4
While upgrading to Torx bolts is advantageous, though what's more important is the yield and tensile strength of the bolt. There are various industrial classifications for different categories of bolt strength. A lot of consumers aren't aware of the fundamental differences between one bolt and another. Syntace explains these differences well: http://www.syntace.com/index.cfm?pid=3&pk=373
Typically, bolts are the weakness in a stem, particularly in the area where the bar is clamped. The torsional rigidity of a stem often relates to the clamp design and bolt strength. For example: bolts spaced widely apart, although it often means a stiffer stem, puts more load on them compared to those closer together. I've heard a lot of stories of stems where bolts snapped.
The 3T Arx II is a good example of why they changed a design of an otherwise popular piece of equipment. Loss in stiffness had to be compensated though certain design tricks.