One of the issues I worked on is that ETA wasn't being displayed. So I took time to implement it, and here's a screenshot of it in action:
Let me explain each of the picture. Top left is the star being out of range for the colony ship which does not have extended fuel tanks. Top right shows a scout already en-route, with 3 turns left to arrive. Bottom right shows you being able to change destination, but since it's already en-route to the first star, it will have to continue there, then it'll go directly to next destination. Hence two ETAs being displayed. However, since it won't stop at the first star (it will simply continue to next star without stopping there for a full turn), it won't explore the star.
This latter is very useful in cases when you have ships retreating, and you want them to reroute to another star when they're already en-route, this allows you to make orders without forgetting about the fleet.
Hyperspace communications will of course simply change the route to be direct to the new destination.