I've
made a separate thread for my listing now, as it's awkward to keep going back to page 3 to see it. I've also made a number of the proposed changes and am still accepting input on any more. I put my name at the top, but really I see this as a collaborative effort.
Each of those classes except the Shadowbane Inquisitor is decidedly meh. They give little-to-no abilities that you wouldn't get from taking the base entry class.
Thayan Knight puts a huge "Kick Me" sign on your back. It gives you minimal bonuses, the most useful thing in there are the Fighter feats that you could just take Fighter levels for. When you would prefer to take Fighter levels than a PrC, you know it's not that high a Teir.
Occult Slayer is OK for it's Mind Blank ability (running off memory here), but you're trading 4 levels of meh to get an ability you can get from an item or party member. I'd rather take 5 levels of Streetfighter or Kensai, and both of those you've listed as being worse, when they're much better - not because they're worth a tier 2, but because you've put it far too high. Same for Knight of the Chalice, except it lacks any key crucial ability that's plausibly worth the investment.
Spymaster is tolerable as it gives a semi-unique ability, but it's still decidedly lackluster. It certainly has the drawback of not continuing your bardic casting/music, inspiration, beguiler casting or rogue special abilities, and so is by definition not Tier 2. I could see Tier 3 for a heavily social game, or for use of the GM, but I'd personally peg it as Tier 4.
Shadowbane Inquisitor exists for one purpose - entry into Blackguard. If you want to play a non-LG Paladin then Greyguard is superior. It truely shines when you use it to enter Blackguard, as you get to double up on the class features for the Shadowbane Inquisitor while getting the bonus class features from having "Paladin Levels". With retraining you theoretically bootstrap your way to Shadowbane Inquisitor 10/Blackguard 10 (though the legality is debatable). Pretty much it's a class that doesn't add anything useful to your abilities unless you're using it for Blackguard entry - since you have a note about Fochluchan Lyricist being Teir 2 if item entry is valid, I would advise a note for Shadowbane Inquisitor being a higher teir if used for entry into Blackguard.
Various similar problems also I could list for Bloodhound and Dread Pirate. They're both lackluster. IMHO in order for a PrC to be powerful, it has to supply something unique that the base class doesn't supply. These classes do not (though Bloodhound IIRC has a nifty ability that can stop anyone you hit from being killed).
Also, you have Mindspy in teir 3 and 4.
Thayan Knight I can see, and dropped it. Occult Slayer also got dropped, but I do think the bonus to saves and the spell turning ability are worthwhile (since you can reflect 10th level spells that way, always a nice thing for a poor melee character), so I may put it back up. Spymaster is dropped. Shadowbane Inquisitor has been split as per your recommendation. Bloodhound offers Freedom of Movement and Divination-resistance, and those two alone justify its ranking to me. Dread Pirate gives you a form of Leadership, and that alone justifies its ranking to me.
