As of Enyo 2.5 you can no longer set selected programmatically and then get the value of the currently selected option. It does, however, work if you set it manually, but if set programmatically after that it will return the value of the last manual selection.
Here's some fiddles:
enyo 2.2.0 http://jsfiddle.net/sbk2t8k4/ — works
enyo 2.4.0 http://jsfiddle.net/z91jm5w5/ — works
enyo 2.5.1 http://jsfiddle.net/nrh04uj3/ — broken
enyo nightly http://jsfiddle.net/bsqg9n18/ — broken
Thanks for reporting. This is in our queue to be reviewed in more detail in the next week or two.
Fixed in 2.6.0-pre.4