We have a lot of courses authored in SL1 and SL2. I believe most of us don't update all the SL1 courses to SL2 to do a minor tweak. There is too much chance that the update will cause hard-to-identify shifts of text and/or images, or more. It is clearly less work to do a minor update in SL1.
It would be so much more convenient if SL2 had a unique suffix... how about .story2 ?
Can't change that now, but when SL3 comes out, I hope Articulate will give .story3 a little consideration.