Thank you for sharing your own opinions, Elendil. First of all, we opted for a stance system because it was the only viable way to implement such significant feature, without disrupting the hero's iconic abilities (something that we were told would never happen). Furthermore, I find the idea of a particular stance system, in dealing with each faction's mightiest heroes, a very clever addition, provided that each system is enough unique in itself and that we don't risk to have unnecessary replicas of concepts in the game. In this sense, Sauron's, Thranduil's and this proposal's mechanics are substantially different from each other. Different mechanics, different effects and different lore-related references. That's the most important thing.
Concerning the leadership issue, we were also expressly told that Gandalf would never be granted that either, for the reasons you too have stated above. It's not also completely true that Narya is only focused on inspiring hope and courage in other people: as the very Círdan says, the Ring of Fire protects also the bearer from the burdens of its mission and strengthens endurance. In fact, contrary to the physical and vast magical effects of Vilya and Nenya, Narya is exactly the only one of the Three which is majorly focused on the individual who wields it. So, for the sake of the concept, we decided to consider this fundamental aspect of the Ring's properties. As much as I hold Gandalf's overall role in high consideration, I think he could easily do without any leadership/guidance features too, since his nature is also the one of a wanderer and a pilgrim.
About values, every positive effect implies other negative implications, and I tried to make sure to balance things within my possibilities. Nothing is obviously written in the stone though. Numbers and values can always change. The central aspect is the concept itself. In the end, I would say this proposal is a lot better alternative than the current state of things, which not only is totally wrong in regards of the lore and quite far from the tone of the game (the War of the Ring), but it also doesn't do justice to Narya in the first place (a level-1 ability). I find a stance system (which involves one of the Three Rings!) tied to Gandalf's magical shield an absolutely greater and more interesting perspective. A very Edain-ish proposal