Actually enjoyed reading this. Kinda made my morning. So alright, let me put some effort into this. Here goes.
To be perfectly clear - my list runs 3 Guiles, 1 Library, no Crop Rotations, no Dark Confidants, 1 Courser of Kruphix and 1
Vizier of the Menagerie.
There's 2 major points to Guile. First off, there's card selection. It's why blue is so powerful - it makes it consistent and allows it to keep up card quality. While Brainstorm/Ponder do replace themselves, they don't generate CA - they allow blue players to maintain card quality. Guile does the same for us, with every shuffle effect (and we do a
lot of shuffling) allowing us to select the best from 3 new cards rather than topdecking a fully random card. Vs. a lot of decks it's fine for us to be down 1 card, especially if we get to look at a more more cards than our opponents. A lot of decks play Wasteland - they're basically dead vs. us at least 50% of the time (being conservative here), so 50% of the time our opponents are down a card as well when they draw/have a Wasteland, basically putting us on par as far as cards are concerned while massively improving our draws. Then there's FoW - that's a 2-for-1 in our favor that we just need to bait out with the right card. This again puts us on par while massively improving our draws. And what if we're down a card? The point of Nic Fit is that its cards are more powerful and more impactful than whatever 90% of the field plays. And unlike most other decks we do run actual CA w/ our sweeper suite, ironing out any advantage our opponent might have had in the early game. As for generating actual CA w/ Guile and assorted other cards - that's mostly incidental. It's nice when it works out, but it's still fine when it isn't. Guile is mostly a tool for keeping up card quality, allowing you to build up pressure until your opponent buckles.
The second thing is card velocity. Nic Fit is a slow deck. Sometimes too slow. For this we can compensate by improving card velocity. Tone down the mana curve and even try to spread the colours of mana needed to cast spells. It's why I run Path to Exile over Abrupt Decay (cheaper and lessens the demand on specifically green mana) and why we ran SDT over stuff like Painful Truths. Falling too far behind on cards played can be devastating. And this is where Guile helps as well. Imagine one of our worst MUs - ANT/TES. Tapping out T2 to cast Sylvan Library is considerably worse than casting, say, Guile and a discard spell. Or, on T3, Guile and
Ethersworn Canonist/
Gaddock Teeg. The alternative is that you
don't cast Library, but that means it's just a dead card in your hand. Odds of that happening w/ Guile are smaller due to the fact that it's cheaper. And then there're plenty of cases of having to choose to play either a 1 mana spell or Sylvan Library on T2. Guile will allow you to play both in some of those cases.
As for Sylvan Library
drawing cards - I often don't find myself doing that until the late game. The problem is though that we need to get there first. And that's what Guile helps us achieve.
And on Pernicious Deed destroying Guile - sure, but often enough Guile will help you find Deed when you actually
need it, in which case it just becomes "Sever a limb to save the whole". Replacing a Deed w/ a Toxic Deluge helps mitigate that somewhat though. It also gives you a use for multiples you might run into. I've blown up (or shuffled away) my share of Tops b/c I had a copy to spare.
That all being said, Guile just looks kinda "Meh" on paper. In this case seeing really is believing. As for anecdotal evidence, there's the game where I had Guile + Courser + Vizier out and the 1 upkeep I got with it got me nothing. And then there's the games where dropping it in the early game (T1-3) allowed me to keep up with my opponent and answering his every move in some form or another and the games (yes, plural) where a more late game Guile allowed me to go Rhino, Rhino, Rhino for the win while my opponent got stuck in topdeck limbo.
