I upgraded a couple of months ago when it was $3k. (Boo!)
90% went from 205-207 to 218-222
100% went from 223-227 to 242-248
Currently at 16k miles, almost a year old (June 2016 delivery)
I needed it when taking a road trip where I had stretch of 215 miles (Jackson, MS to Memphis, TN).
I think it's TOTALLY worth it for $500. No brainer!!