Jun,
These are features we'd love to see in bug-tracker, so I (like you, I'm sure) would prefer to see the effort gone into adding those to bug-tracker instead of maintaining two pacakges.
1) Storing prefs: the idea was to put this functionality into the list builder, so you can offer this option for any listing or table where this makes sense.
2) More than one user: We deliberately left this out, because there was a sentiment that there should always be just a single point of responsibility. You can still 'watch' a bug without being assigned (although you cannot grant a watch to someone else, which might be useful). Besides, we couldn't think of a nice way to implement the UI with form builder. (Now that I think about it, I think we forgot to look at ticket-tracker-lite.)
Anyway, this was just to encourage contributions in these areas.
/Lars