Do the new speeds affect blackout or redout thresholds?

No; they're still where they were. Afterburner covers those areas. You'll still black out if you're pushing too hard. They want to make it more playable. It's a normal part of game dev. They're trying it out; they'll get it out to Evocati, PTU, and live, and they'll get feedback from everyone, and if changes are still necessary, they'll make them. Nothing is final.