People, I disagree with, it the CK was a perfect program sure, but it isnt and it can unintentionally break things.
Mod authors and the more knowledgable group, sure, they know what to look for, but the average user isn't as careful.
Yes, if youre porting a mod, its a good habit.
Like you said SPGD is broken, also users fail to clean their data folder which results in improper facegen which then leads to black faces.
It seems like the only reason to really update is because of WEAP\CRDT data changes, but I havn't really played with that.
Everything seems to load fine, since something like WTHR\VOLI loads regardless of the form version.