You've got the latest iteration: http://www.revelatedesigns.com/blog/index.cfm/2012/12/19/Viscacha-update

I have 4 guys trying to get from Tucson to the start of the 300. If there are a couple more people interested we could try to get a shuttle together. Does anybody know what shuttle company was used last year?

With regards to the elevation gain difference, I have been seeing the same thing for the last several months. I finally emailed Garmin's support the other day and they said a firmware update had just been released to address it. Sure enough, the change log on version 2.8 specifically mentions fixing the elevation gain issue on the etrex 30.