Well, if you are THAT starving for 20 points of dodge rating...sure? Rune Strike is a special attack that procs after you dodge or parry and ques up on your next auto-swing correct? With a 3.6 weapon speed you would take approximately 12 seconds to get up to your potential 220 dodge, as opposed to having 200 instantly. I personally think the new librams / sigils are severly lacking in upgrade quality.
The problem is you're not taking into account the actual "chance" for the Insolence proc. It's 80%. It has near perfect uptime (20 seconds is a long time) and no ramp up.
With the Bone Gryphon, you have a ramp up, which means any lapse in uptime results in significant dodge rating loss. You gain 20 rating if you maintain a full stack.
Also keep in mind that maybe in tank and spanks outside ICC, it's fairly easy to build and maintain that stack, in ICC, you have a 20% dodge chance reduction, which translates into a significant loss in Rune Strike chance, making it much harder to maintain and much longer to build that stack.
Finally, the Bone Gryphon costs Emblems of Frost which are much better spent on T10 and the badge trinket. Insolence costs Triumph, which are easy to amass now.
There is no real question here. Insolence is the way to go until you're swimming in Frost Emblems and even then, the value proposition is questionable.