jhall, too bad you dont like paladin
Good news is no one will force you to play it =p It's one of my favorite classes, I really like the decisions of when to face tank to keep tokens alive, when to set up equality, trying to bait silences or hard removal for tirion, and so forth. To me classes like hunter, where you just try to spew your hand in the most efficient way possible, bore me. But to each his own!
hardwared, I know kreme has been pushing for Troggzor, (and all in fairness, it's not like Trogg is bad!) but Dr Boom is roughly >>> Trogg. Probably not enough greater thans. Regardless, it's not my list but if you were to swap out a 7 drop I suppose it stands to reason just using any other roughly similar late-ish game bomb does the trick, to maintain that deck's curve.
Vix, almost always you simply mulligan for the early game. Chow is an auto-keep vs everything, owl is very good to keep vs warlock, hunter, warrior, priest, and shaman (the classes its not as important are typically the mirror, druid, rogue)
Minibots are godly in the early game, I'd keep jugglers, and so on. I only keep 3s when: I have the coin and it's muster, I have at least the chow or a 2 drop already, I'm against what I know is handlock so I'd keep BGH, and Aldor is always a keep vs druid. (it's the only remedy to an early insane innervate play)
I've wavered back and forth and at this point consecrate is too good to not keep in both the mirror as well vs warlock. Truesilver is often worth keeping vs mage, I'd keep harrison against warrior and paladin, (and hunter IF I have a chow, or already a strong other 2-card combo), and one of the tricks of the trade is you should always keep Tirion in your hand vs priest.
Loatheb is a keep vs rogue, and if your hand is good enough, it can be worth keeping vs druid. MCT is a keep vs a deck if you know it's a token deck AND you're super pessimistic, (normally I throw it back, if I have a 1-2 curve I may keep it just to maintain my turn 3) shredders can be keeps in midrange matchups if you have the coin (absent of early game plays even, they are just so good!) and that should probably cover it.
Basically the only cards you never want in your opening hand are Kel Thuzad, Lay on Hands, Dr. Boom, the PSG, Belchers, or Healbot. Everything else can be ok to great to keep! (And even healbot or belchers, when I have a perfect hand, is a reasonable keep vs hunter, although you must prioritize the early starts rather than having the taunt or heal for turn 5)
As far as your card subs:
Sylvanas is always excellent, the majority of my Paladin career I've had her in the deck. She's awesome, just recently have used PSG over her and it's been close, so this is fine. Can even use both if you want to shift right a little.
The MCT wins games for me, but it's simply a tech choice I enjoy but can easily be swapped out for another weapon, a different tech choice, another chow, or some late game legendary.
Harvest Golem. Is just not that great in the current meta. When you look at best-in-slot card choices, Harvest is always going to be high given it's 4/4 of stats for 3 mana, (which is 2nd best behind Mukla!) and since it's stickier than a dancing sword or ogre brute (with the stats divided up) it's arguably better. It also has the mech tag which although not relevant in this deck is obviously a good thing. The
problem at the moment is a majority of cards that you need to kill now have 3 health, rather than 2, (it used to be the other way around, which was why it was such a MVP) so in decks where you dont have mech buff cards, it's no longer as appealing in the 3 spot. As in, a 3/4 (ie. spider tank) would be better if you're looking for a blase 3 drop.
Even still though, in my experience double aldor, double muster, and a bgh is enough 3s, so if you look to add more to me coghammers, mct, or acolytes simply hold more value.