I would just do the training through windows before you buy anything. Just see how it plays with you. VA uses windows voice recognition, so I would go through the "training" a few times and see if it would be worth the buy first. But keep in mind that you can make the voice command for Voice Attack anything you like. So, if it has trouble recognizing a word, just change it. For example, my computer can't recognize me saying "Chaff" for the life of me. Just doesn't get that word, so I dont use it,, but I've seen other people use it just fine.
As for the reaction times, its really not that bad and some things are faster. For instance I can still wait until the last second to say "Countermeasures" or "all counters" and it will fire a Flare, cycle cm's, then fire a Chaff. Much faster than I can do.
***But my favorite is "Departure handover". My ship will take off to a height of 30m, retract landing gear, then send power to the engines. All the while talking to me lol.