Chris B,
As a rule, transfer bar actions are relatively immune to dry firing damage. The Ruger New Model Single Actions, for example are almost impossible to damage by dry firing. I should know. Many of my shooting friends have tried. I have yet to hear of a broken firing pin.
On the other hand, I have personally replaced several frame-mounted firing pins and hammer-mounted firing pins in non-transfer bar single actions. The constant slap-slap-slap reulting from pin-to-frame impact is rough on both firing pins, firing pin holes, and retainers.
If dryfiring is worrisome to you, try installing a strip of hard foam rubber between the hammer and transfer bar. Snap caps also help, but do not eliminate the hammer-frame pounding effects.