Ritual bonus from magic sites

[Hellboy]

Kalin said:
Of course this oversight has been around since... pretty much forever, so they just kinda kept it around as one of those hidden rules to make new players crazy. A throw back to the old days perhaps? Who knows... It's just that everyone who's been around for a while knows about it, and frankly it's not really that bad IMO, so there's really no outcry for it to change anytime soon.

But if I understand this correctly, it really is quite bad.

I played a few Dom 2 games a while back (apparently before this fact was discovered), and as I recall in the end game, it was the extra gems that far and away dominated the question of whose global spells stayed up. One of the more practical ways the weaker nations could gang up on the front runner was to pool gems in order to dispel that front runner's globals. I know that in my games, in our diplomacy, we always assumed the formula applied was even more generous than your Kalin, in that bonus percentage applied even to the extra gems, something more like:

extra gems = [Gems spent - (Cost x (1 - 0.2))] x 1.2

The upshot of what you are all saying is that these sites are next to useless in MP games, at least for global spells.

Has anyone tested this empirically in Dom3?