All right, I really need to brainstorm some more and I'm fresh out of ideas. Between all of the shit I'm getting IRL and from the Halo clan I'm in, I've been burned out on ideas here.
As stated in the other thread, Truespeech is still a skill-based check. However the results of the skill check itself do not determine if an Utterance works or not, it determines how long it takes for the Utterance to "recharge". This basically removes the need for the Law of Sequence entirely, and now that the DCs for each utterance are going to be set in stone instead of being variable the Law of Resistance needs tweeking.
Pumping skill checks, therefore, will still be encouraged but won't be absolutely required. Given how much I'm changing things up, being able to hit a DC 50 Truespeech check will just be gratuitous as most utterances aren't going to instantly recharge if you meet the target DC (it will be like a Breath Weapon for most of them, others just recharge at the end of the encounter they are used in, and a rare few will have a 1-round delay on the recharge; very few will be able to instantly recharge).
Personal truenames are being tweaked; most effects that care about it will be personal-target effects. In the original it just raised the DC of the Utterance (both the skill check and save DC), but in this it improves the actual effect the utterance will have. Knights will have the most utterances that care about it, Truenamers will have a handful, and Hexblades might not get a single one. This change is largely because it's a huge pain in the ass to balance out the rules for using someone else's PTN, although the fact that only a handful of BBEGs would have a PTN worth researching is also a reason. The fact is researching the BBEG's PTN is very hit-or-miss as the DM can always override the rules and say it's impossible, even if the skill check result is obscenely high. I'd rather not put that kind of rule into this, as your own PTN is something all three classes will be learning anyway. There will be a mechanic to using your allies' PTN to "share" utterances, but this will be limited to a PrC.
The various Metautterance feats and other goodies Truenamers got in the original are being shifted over to Skill Tricks, most of which will require ranks in the Praxis skill in addition to the obvious Truespeech requirements. This makes it easier for a non-Hexblade/Knight/Truenamer to use Utterances, but given that those classes will have a heavy-handed limit on Utterance access anyway it won't cause a problem. Metautterances themselves are going to be unusual by comparison to previous incarnations of metamagic: Some metautterances will raise the DC of the utterance they are affecting, others will increase the recharge time, and some others will affect the duration of the utterance.
PrCs are getting overhauled in general, but the Utterance Users will be the most affected as the source material had no PrCs that advanced Utterances Known (although all of them provided unique utterances). As I am trying to steer away from the whole "PrC out as early as possible", most PrCs that advance any form of spellcasting are going to lose some CLs in some way (Theurge classes will be the only ones to have 10/10 progression, and even those ones will have prereqs that require you to lose CLs anyway).