Hi,
Not a fan of the proposed change to manyshot at all.
It seems harmful for hybrid melee/archery builds which use manyshot as a burst. Other alternatives to handling the issue of allowing rangers to choose between burst and constant damage have already been proposed in this thread.
The reduction in projectile numbers for that period will significantly reduce additional damage from sneak attack, arrow imbues, and on hit weapon effects. So not only do archers already have a comparatively low RoF outside of manyshot, that same disadvantage will now be extended to it.
As other people have already observed, a large amount of doubleshot is already available to archers. The buff to it during this new manyshot will be pretty marginal in those cases, making manyshot little more than a ranged power action boost.
No thanks.