I tried a Guild Rush deck this week too, and couldn't get it to get past 50%. Desert Merc feels bad when you don't have any 2-3 mana guild dudes in your hand. Vault Vagabond seems out of place here, I'd definitely go for the 4/2 Hidden instead. Prison Escapee while cool when you can pull off the combo seems quite slow for an Aggro deck. Good luck!