I think that the intriguing aspect of playing CoW in the side of a control deck, as another weapon to use in the control mirror ( any control deck
can die to the CoW-Waste route ), is that the opponent have to add useless/subpar cards in a matchup where siding in/out dead cards is THE KEY to win.
Opponent can't easily rely on Wishing for Removals because, during game 2 and 3, it may be too slow and too conuterable to be the right choice.
Opponent have to side in ReBs and Disenchants and "Bombs" ( if he have them in side

), and it take a lot of space to be done. Usually space is the only thing that I not have when deciding what I have to side In/Out.
Opponent can have MORE dead timed draws than before. And usually some tutors are sided out ( Mystical and Vamp ) because they produce card disadvantage; the last statement improve the randomness of adding cards that could be drawn, maybe.., too late.
Jayemdae Tome/Scrying Glass usually where used to produce permanent cards advantage.
CoW is Permanents Advantage that can easily be translated, in a middle-log term game, to a Cards Advantage if we count all the umplayble cards in the opponent's hand as "+1" for us.
And compared to the Old Tomes it is better because it DOESN'T COST any mana to be used once resolved.
So, in a different but MORE efficient way CoW achieve their same goal: With your better mana development you can be able to do more things than your opponent and it is usually a victory strategy.
This is one of the reasons because I'm doing some space in my side and trade for 2 foiled CoW

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I think that playing 1 Shaman and 1 CoW maindeck is a bad Idea.
Two Shamans are in for a specifc porpouse. To consistently stop the opponent's fast mana development.
If you resolve CoW when Slavery or Storm.dec try to win it couldbe useless. The Shaman alone could usually be the best play to do in this situations
-CoW requires that I have to Tap3Mana with Sorcery Speed agaisnt a possibly unknown opponent or agaisnt an opponent that can superpass his LD effect with ease.
-I have to stop artifact's recursion and fast mana to be able to deal with Storm.dec and with MW.dec. Shaman is the second best spell available for acquiring this thing. The first is Null Rod. In this situations CoW is one of the "so so" spells of the deck.
-Aggro and Combo can use lands OneShot and produce brokeness and lethal damage with great consistency, expecially thanx to their fast mana. So Shaman are great choices and cannot be
replaced with CoW.
The last point underline ( IMHO ) that the nature of this card is GAME BREAKING expecially ( if not
only ) for the control mirror matchup. Definitively a Sideboard Card, even for 4C-Control deck.
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The dilemma of the CoW-Strips rate is difficult to explain ( expecially with my english ...

).
I think that smart player can force you to lose land drops and use 2 recurring strips effects on his own Fetchland. This is a smart move IMHO that can be easily prevented if ALL the available Strips Effects are present in the Deck.
IMHO, 5 Strips and 2 CoW, in a POST side scenario, is the correct number to play.
I played, during this week, against 'Comboish' versions of CoW.dec. They are patetic because all your fast mana acceleration is ( at least for the versions agaisnt which I played ) totally untouched and this let you continue to play a bit.
Analyzing a possible 5Strips+2Shaman+2CoW scenario, I think that this handicap is easily superpassed. Until now, 4C-Control is one of the best ( only???) candidate to play this configuration, expecially because we doesn't need to create a different deck that can abuse of CoW.
I think that Draining a 2cc spell to try to resolve a CoW on your 3rd turn agaisnt control with some mana open for other tricks, is the best NOTbroken-NOTrestricted-involved play of this deck.
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There will be times and gamse when the complete set of FoWs could be sided out to do space for more useful and sinergic cards...

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