Um, no, they said in SR4 that they did stack. And said they were compatible. I looked it up to be sure.
Yes reaction enchancer says it compatible, but wired reflexes and synaptic booster as well as the adept power and spell version all say that they dont stack with anythink, thats all from my version 1,0 corebook.
Yes, but Reaction Enhancers do not increase initiative, they increase reaction. The initiative boosters say they don't stack with any other initiative enhancement, not reaction enhancement.
To get a little history (or trivia, if you prefer) on the cyber, back in previous editions the number of actions one could take in a round was based upon how high you rolled your initiative. Reaction Enhancers stacked with everything and added a flat amount to your initiative (rating 1-6). The other reaction enhancements added some number of dice + a little bit straight to initiative. The crazyiest initiative I ever saw was 5D6 + ~27, with every 10 points giving you an action. This was back when they frontloaded bonus actions.
With the very hard limit on attributes, Reaction Enhancers are a nice way to top off your Reaction attribute to their racial augmented maximums. They are NOT worth investing in by themselves, as they do not grant bonus actions. They only become nice when combined with initiative boosters that grant those actions.
The odd typo, if such it is, needs to be addressed in a FAQ or something.