Thank you all for your comments. Leslie Ann Smith, I noticed that I failed to note the spring tension on the kneeling variations, and that was on one red spring. If you're not on Gratz or Fletcher reformers, you may want a blue (lighter) spring for the arm series. If I can clarify anything else, I'm happy to.
Not sure about Stott springs, and I just realized that you can't do the kneeling variation with the foot on the rail since there is none! (a nice feature in many ways)