Taking the argument of being able to hit them at such ranges out of the question, I believe pheasants can be killed reasonably consistently at these kind of ranges IF the correct kit is used. On many of the large high-bird shoots around me 40-50g loads of #3 are common, however many opt for a no.4. A few years back (pre lead ban) a great deal of wildfowlers swore by no.3 for foreshore geese - so why wouldn't it be able to deal with a pheasant? Heavy guns, full chokes and loads such as those I have mentioned make the job doable. I'm not saying this is my cup of tea at all, and would much rather shoot 'nice height' pheasants (40-50 yards) with a moderate load, but each to their own. We shouldn't knock those who are skilled enough to do it, it is those who don't have the skills but do it anyway (wounding birds in the process) we should discourage.
Back to the matter in hand... fibre wadded cartridges are renowned for not patterning as tightly as plas wads, but the striking energy of like for like pellets will be the same. It is only the difference in patterns that will make fibres less effective at range.