I think it would be well worth having the set-tru feature. There could be plenty of opportunity to turn a part end for end and try to make it run concentric in the second setup.
The set tru feature does not affect the accuracy of the scroll itself, so you should have a chuck at least as good as a plain one, if they take care in the manufacture of it. Examine and compare their accuracy specs just to be sure.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)