I completely agree that there's no reason to build an alternate green unless it's going to be the equal of the other green. You definitely don't want golfers to be disappointed that the hole's cut on the inferior green the day they happen to be playing. (Though it's a bit different at a private club.)
Sorry Adam, did I miss your question earlier?
Anyway, I don't know if there's 'justification' for my proposal. But there's an unused piece of this particular club's property that presents interesting opportunity to create a hole with two greens. This would involve preserving the existing green and installing a new one, left of the current green. The powers-that-be at this club were quite excited about this possibility when I originally pitched it. So now I'm looking into more details. As stated above, I certainly want to be sure that we don't create a hole where people are disappointed if the hole is on one green instead of the other.
I think the only think I have going for me in this case that Riviera's 10th and Pine Valley's 8th and 9th holes don't is that we're also proposing alternate tees at the same hole. So. more like the 11th hole at Devil's Pulpit, this siutation will likely be more like alternate holes than alternate greens.
Thanks for all the responses.