I don't mind Trust as an opener, it's actually pretty cool, imo. Also, I'm digging the Countdown songs, mainly because I haven't seen some of them yet. I do think they should replace Skin, though, that one's been played out. Ashes was incredible when I saw it in 2008, so if that stays throughout Gigantour I'll be happy. Same with Sweating Bullets. One of my fondest Megadeth concert memories was headbanging in unison with (what seemed like) the whole crowd during the middle of the song.
Overall, it could be better, but I won't complain too much if this is the Gigantour setlist. But by then I could see some of those Countdown songs being switched out for Super Collider songs...
9/20 - Overkill or Nik Turner (or both!)
9/23 - King Crimson