Jumper strut vs. running backstays

[Brion Toss]

Hi,
Most jumpers are trying to do two jobs: keeping the mast from bending to leeward at the top; and opposing the forward pull of the forestay. Runners are only about the second of those jobs. With a sufficiently large angle, and sufficiently small forestays'l, jumpers can do both jobs without help from runners. On some boats, the jumpers are calibrated to work up to a certain load level, at which point the runners need to supplement their efforts. On still other boats, different standing rig components handle the lateral loads, and the runners (or, rarely, a single, forward pointing jumper) take care of the forward pull.
So, no simple answer here. Did you have a particular boat in mind?
Fair leads,
Brion Toss