I don't disagree with anything you said.
But when you start bumping up "MIGHTY" bow damage, it questions the damage of a machine loaded crossbow.
I understand, and after further thinking on it, I agree with you. I think the thing to do is just remove the increased damage dice for the Mighty property, and use their original damage dice as is.
I'm still sticking with the replacement of the bow's STR score for attack and damage though (if higher than one's own DEX score). A Mighty Bow (Strength Bow) would have greater penetration ability, so if the bow's STR score is higher than one's DEX, then I think it should supersede...at least if one wants it to. If someone decides they want to use the lower score, that's their choice; though to me, that seems like foolishly handicapping one's self.
This is still Over Powered...
I understood what you were saying the first time. It really wasn't necessary to completely repost your argument, or shout/bold-highlight your points.
And I still disagree with you.
The Mighty Archer Expert is no more powerful than the Crossbow Expert Feat.
Gaining an extra attack from the Mighty Archer Feat is effectively no different than the Crossbow Expert Feat, which also results in an increased rate of fire.
Not to mention that it takes two Feats for Mighty Bows (or three Feats for non-martial classes wanting to use a Mighty Longbow), and only one Feat for Crossbow Archer (since crossbows are simple weapons, and don't require a separate feat for proficiency).
The Feat cost more than makes up for any perception of overpowered-ness, and in-my-opinion, effectively flips the onus in the other direction.
I will however, add a blurb requiring proficiency in the basic bow prior to taking the Mighty Archer Feat.
So, absolute, beyond-a-doubt, I'm-done-with-this, final version:
MIGHTY ARCHER
Prerequisite: Proficiency with the base version of the Mighty Bow (either shortbow, longbow, or both).
Thanks to extensive specialized practice with powerful bows (Mighty property), you gain the following benefits:
• You can utilize bows that you have proficiency with, that have the Mighty property with a STR score of up to 18.
• You gain an extra attack when using the attack action on your turn, for a ranged attack with a shortbow or longbow that you have proficiency with, in addition to any extra attacks provided by your class.
MIGHTY ARCHER EXPERT
Prerequisite: Must possess the Mighty Archer Feat.
Thanks to further specialized training with powerful bows (Mighty property), you gain the following benefits:
• You can utilize bows that you have proficiency with, that have the Mighty property with a STR score of up to 20.
• Being within 5 feet of a hostile creature doesn’t impose disadvantage on your ranged attack rolls.
• Before you make a ranged attack, you can choose to take a - 5 penalty to the attack roll. If the attack hits, you add +10 to the attack’s damage.
WEAPON PROPERTIES
New Property
Mighty. A shortbow or longbow with this property has it's own STR score. A character must either possess proficiency in bows with this property, or have an equal or higher STR score, to utilize them. You may add the STR bonus of your bow (if higher), instead of your own DEX bonus, to attack and damage rolls when attacking with a mighty bow. You may not add your own STR bonus (if higher than the bow) to attack and damage rolls. The range of any shortbow or longbow with this property is increased to 200/800. The price of shortbows or longbows with the Mighty property increase by 25gp for bows with a STR score of 12, with an additional 10gp for every two points of STR above that (+25gp for STR 12, +35gp for STR 14, +45gp for STR 16, +55gp for STR 18, +65gp for STR 20, etc.).
Cheers