Thanks for giving your feedback and the detailed case of use.
In answer to your question, whether story estimates are driven by task estimate rollups, the answer is different, and it changes based on the team preference, maturity and methodology they use.
Currently TeamPulse let teams use different metrics for story planning and estimate - like points, and hours - for planning and tracking tasks. As those values not necessary are in same metrics, the roll-ups might not work as expected.
What we plan to implement is to have two values for the Story item. One to be the initial estimate base on the units you use and the other to be Story task estimate – the second one will be a roll-up from all the tasks related to that story and will have an progress bar against it. This way, both values will be visible and be an object of future analysis and comparison.
As for the bugs there could be a work around by adding task for fixing the bug in the story, so the roll up would included in the unplanned work.
Let us know if the proposed solution will be valuable for you and your team?
Thanks a lot,