Hi,
I just found a bug on <ion-header-bar> migrating from the beta13 to beta14 
The width of title is calculated from the number of characters in buttons but it’s hardly wrong when it’s an angular expression…
See this codepen for practical exemple : http://codepen.io/anon/pen/OPbKxy
The workaround I found is to set angular expression via ng-bind instead of {{ }}
I opened an issue : https://github.com/driftyco/ionic/issues/2881