Well it really depends, I can usually beat control decks like Turboslaver, either by winning before they get a null rod into play or boarding in oxidizes (or crashes, I can't make up my mind). The U/x Control decks are hit or miss, mostly miss though. The problem is FoW obviously, and 2 mana counterspells to a lesser extent, though I have been able to win pre-board a couple of times before. Post board, I board in xantid swarms and welders for desperate ritual and 2 cabal rituals. This makes the matchup somewhat better, but it is still a less than positive matchup. My win percentage I would say is around your percentages, but I haven't been keeping track, really.
Also, how has tainted pact been working out for you? I can understand it's utility in a deck with few lands, but how often does it just fuck up? And also, I would honestly take out some of the tutors, I have never really needed more than one in my opening hand, and 11 gives you more than ample opportunity of getting one in the opening hand (You will draw on average 1.8 tutors and/or belchers in each opening hand).
Seething song for me has been just incredible, it's basically like another dark ritual for the deck, because it nets you 2 mana upon casting and though it does cost 3 mana, you will be getting up to three mana if you ever hope on casting the belcher.
