Well, I have seen the show 7 times as well...(Crazy, I know....) and Helena has been Datchery 4 out of the 7 times I saw it.
Bazzard should easily be Datchery almost every time, as Kelly2 mentioned, the author is almost telling us to vote for him. However, early in Act One, there is a hint/mention of Helena disguised as a boy highlighted by a musical sting/chime that Jessie Mueller brilliantly uses to the maximum effect. Maybe the audiences are really paying attention to detail. That, and I think Ms. Mueller is very likable and funny from the instant she steps on stage, so people like her and root for her to do more in the show.
As for the murderer outcomes, if Rosa ends up being voted for the night before, she will most likely not be the murderer for the performance directly after...I feel like if a character is very popular, and they have a number from 4 and up, they have a really good chance of being the murderer, especially if the audience is not as theatre-savvy.
Crisparkle has a great final statement that always goes over well....so does Helena and Rosa.
So jealous you got to see Rosa as Datchery. I wonder how THAT happened, and how do we get it to happen more often?!?!?!!
"Someone tell the story...Someone sing the song...."