Could you please clarify? Do you see the erroneous red lines with that option enabled, or with it disabled? The answer will tell us where the bug needs to be fixed.
It depends on your needs. Right now, using SCIFIO is better in some ways, and worse in others—hence the toggle. There are certain classes of TIFF file which ImageJ 1.x cannot normally read, but SCIFIO can, so enabling SCIFIO helps with that. And there are some image formats which have SCIFIO format plugins, which can thus be read when that option is enabled, but cannot read with it disabled. However, ImageJ 1.x is optimized for time performance reading TIFF files, so for the TIFF files it can read, it will typically do so faster than SCIFIO does. We plan to improve this situation in the future, but no one is actively working on it at the moment.
Are you asking when the SCIFIO option will stop being labeled "BETA"? That will probably happen when SCIFIO's time performance is comparable to, or better than, ImageJ 1.x's.
Or are you asking when ImageJ2 as a whole will stop being versioned like
2.0.0-rc-XYZ and finally go to
2.0.0? That will happen when the
imagej-common data model has been redesigned; the issues labeled
data-model are the ones which describe related work there. I do not have a timeline on this work, except to say that it is currently number 5 on my list of primary projects.