I agree. Adding diversity to a wing always strengthens it.
To be honest the Vulure is the stronger ship of the two. In the hands of a pilot like Kestril I doubt it will ever be beaten by a Courier. (Really want to see a fight between Kestril and Fox by the way and would love to see how Hazara in his Courier goes against the Vultures.)
The jump range on the Courier is very similar to the Vulture (if you equip the same bulkheads), but the fuel tank lasts twice as long on the Courier, and you can fit an A3 fuel scoop on the Courier without harming its combat capabilities. This means that the Courier can quickly cover the distance to Fed space and start some trouble. Travelling as a wing of two Couriers, you can move quickly and protect each other.
Hence why I suggest for Undermining missions, we use 2 Couriers. If others want to join the wing in other ships like Vultures and Clippers, then they will add some great attributes to the wing when they eventually get there.
For defensive wings inside Patreus space, Vultures can quickly get to the conflict, hence they would be the better choice.
Obviously there are better choices than wings of two Couriers or two Vultures, but these two ships are already owned, or soon within reach, of many of our members, and the running and rebuy costs on these ships aren’t too astronimical, hence why small wings of these should be considered.