So, I just played this game
http://dominion.isotropic.org/gamelog/201112/21/game-20111221-001722-02f9bb77.htmlI decide Bridge/Fool's Gold, RomaNorgy does Saboteur/-. I do a standard "buy lots of Fool's Golds, buy Provinces" deck.
Roma goes for an early Saboteur attack that transitions into a deck that wants to do heavy Saboteur damage. From what I could tell, it uses extra actions to play a bunch of Bridges and Saboteurs, uses Bridge money to buy more components, and eventually leads to Saboteurs that will only hit Provinces. Turns out that setting up that engine is too slow.
However, the interesting bit is around the early/mid-game: In a pure Fool's Gold deck, the only Saboteur targets are the Provinces. This is both good and bad: you always hit VP, but you never hit the buying power. In this game I lost 4 Provinces to Saboteur, not to mention the Golds and Duchies I lost after I gained those as a replacement.
If this game shows anything, it's that in a Fool's Gold board you can't let your opponent get all the Fool's Gold. I'm pretty sure no amount of Saboteuring stops you once you have 10 Fool's Gold. But if you bought some Fool's Gold yourself (say 3-4), and got a Saboteur as well, would that make up for the bad Fool's Gold split?