A few questions about reaction bonuses. Does the +1 to reaction for driving with a datajack also apply to riggers, in addition to the VCR bonus? Does the +1 to reaction from a suprathyroid gland apply while rigging? Does it apply while decking?

I would say no to all three.

no, no and no

No to this first one, maybe to the other two. Depends on the wording of the superthyroid gland. Remember that the reaction bonus gained via muscle toners would apply to non-DNI decking (Prue DNI is Int iirc). Is rigging reaction INT based as well? If the reaction switched to INT based reaction, it wouldn't.

Yeah, I think it would apply to rigging, but not to decking, since it's physical.

According to the rules as written, no to all three.

I've always had misgivings with the rigger rules on reaction boosters.

I really don't understand how working out and getting your quickness up is any different from buffing yourself with muscle toner. They both hit the racial cap and it's no less an indirect boost than the Cerebral Booster.

If they really wanted to cut out those Other Things while keeping the Cerebral Booster, the rules should just say to use your Intelligence score in place of your normal reaction when Rigging.