[Namikaze]

Just got a reply from one of the freelancers.  This isn't official until it enters errata, but here's the explanation that I received:

"Any improvements to Reaction do thus increase Initiative, but the bonus from a Suprathyroid Gland does not directly affect Initiative Dice, like Wired Reflexes or Synaptic Boosters.  Thus, I would argue that the bonus is stacking so long as it doesn't give more than +4 bonus.  The only circumstance in which someone can break that +4 bonus is with drugs."

It sounds like a good rule of thumb for almost everything.

[faffner]

...the bonus from a Suprathyroid Gland does not directly affect Initiative Dice, like Wired Reflexes or Synaptic Boosters...

So, it does affect Initiative Dice indirectly. Or not. Dice? Whatever...

[Xenon]

Initiative dice?

To be honest, this just made things even more confusing... But thanks for sharing.

Is this guy's whole answer? "Thus" is normally used after explaining something...

[Namikaze]

"Any improvements to Reaction do thus increase Initiative

- Pretty sure the "thus" refers to the fact that an improvement to Reaction also increases Initiative.

, but the bonus from a Suprathyroid Gland does not directly affect Initiative Dice, like Wired Reflexes or Synaptic Boosters.

- This means that an item that boosts "Initiative" refers to the Initiative Dice

  Thus, I would argue that the bonus is stacking so long as it doesn't give more than +4 bonus.  The only circumstance in which someone can break that +4 bonus is with drugs."

- So the bonuses from Suprathyroid Gland and Improved Reflexes stack, so long as the character doesn't go above the +4 maximum for Reaction