We were on the first trip of the Sacred Valleys tour this year, and we decided that we would be looking for more first trips/new tours in the future. I think they made a special effort to have their best guides on the trip, just in case. I know all the guides are good, but it became obvious through various conversations that Aimee is one of their "go to" guides. (They wanted her to lead the ABD that the members of the The View took in June, for example, and she often trains new guides.)
We were also told about the "dress rehearsals" that Disney had run, and changes they had made due to feedback, then had tested again with another dress rehearsal.
So I wouldn't worry about being a guinea pig at all. Enjoy your trip!