Sounds like a fine combination for the 99, though not quite enough for a commander
You can Stifle the ability on the stack, or kill my Sungold Sentinel before the ability resolves (and the Sentinel gains hexproof), but the Sentinel's activated ability doesnt care about coven after activation, so nothing you do to my coven will matter in this scenario, But, on the other hand, if I trigger Redemption Choir, you stop the trigger from resolving if you mess with my coven while Redemption Choirs ability is on the stack
The first will cover whats going on right now, while the second will cover what may happen in the future if things do get worse
Weaver of Harmony [Less than $1] I think this card has obvious applications beyond pumping your other enchantment creatures
With the emphasis on, Me. These are just my personal favorites