Sayelle was used by several companies, but it's a heavy worsted. RH super saver would work, or Caron Pounder, or any of the large skeins by the different companies. Using size 10 with a worsted weight works okay even in plain stockinette. With this pattern you probably have a lot of cables and/or bobbles, so using a little larger needle makes them easier to do. Besides, cables pull in a lot more than plain stockinette, so it would be too narrow if you used smaller needles.
sue- knitting heretic