Beyond that, can you tell me any differences in position expectations for horse and rider between the two disciplines? How different is headset, rider hand placement, etc? In pleasure I know only the horse is "supposed" to be being judged, but what about in reining? Any tack requirements or items that are not allowed? Any info would be appreciated!
One of the things that is stressed at the NRHA Judge's School is that you judge the maneuver NOT the style. In other words, it doesn't matter if your horse's head is up or down, if your free hand is beside your rein hand or clamped to your belt buckle or somewhere in between, etc., etc.
However, there are definite rules about what you can and can't do (such as touching the saddle at any time - 5 point penalty or straightening your reins while the horse is moving - penalty score zero!). There are also specific rules regarding the equipment and dress that can and can't be used. When you are ready to try your hand at reining I suggest you go to the NRHA website (www.nrha.com) click on the "Reining" tab then on the "Forms & Documents" link and finally click on the "NRHA Handbook" link. Sections 95 (Rules for Judging), 101 (Patterns & Descriptions) and 125 through 144 will explain all the crucial rules that you will need to know to try to stay out of the penalty zone.
I would also suggest that you look for a Judge's Applicant Seminar in your area. It is $150 and 2 days well spent to educate you in what the judges are looking for. As many of the top judges teach these seminars it is an excellent opportunity to talk to them and get their feedback. A few weeks ago a seminar was held, I believe in MI and I am told they had 60 people in the class while only 15 took the test and so were looking to become judges. The rest were just there to learn.
Always remember that Reiner's are a breed apart and even at the top shows, the top riders will always take the time to talk to you and to encourage and help you.
Good luck in both you WP and Reining endeavors.