This subject is without a doubt the most contentious and argued over subject, especially in UPT.
First, Rifle sits in a bowl, so it's not an ATC gradient and, civil airspace, ATC gradients are less common than in the military where lots of special use airspace is nearby.
Second, the gradients differ because the procedures differ. The charted SID is based on RNAV 1 while the text version is VOR/DME based and routes differ. With different navigation, different splays and accuracy standards apply; also the slight differences in routing mean different terrain might affect the climb gradients.
GF