I've read all of those articles in the past, and I have some concerns.
Regarding this article: http://thebuildingcoder.typepad.com/blog/2010/08/editing-elements-inside-groups.html
I have tried to use the Ungroup-Regroup method for multi-instanced groups, but I get an error when I try to reuse the same name. I can't save it as a different name, because it will break the link to the other groups, that I want to continue to have its associativity. Also, when I ungroup a multi-instanced group, it only ungroups that one group, and leaves the other groups linked together. As I cycle through those linked groups, they all become independent of each other, and once again, lose their inherent associativity.
So unless there is a way to ungroup all the associated groups at once, then regroup them after the changes have been made, i"m not sure how that workaround actually works in practice.
To explain better... Let's say i have one group (named "A") in my Revit file that is instanced 3 times. Each group has three walls. I want to change the Mark on the first wall from "" to "Z." I use the API to ungroup the first instance of Group "A." I ungroup the first instance and change the Mark. Then I regroup. I cannot call it Group "A," so I name it "B." Now "B" does not have the associativity with the other two groups named "A."
I have the parameter modification working for objects in a single instance of a group, by using the failures transaction catch described in your blog post, but my main problems lie in the inability to go into Group Edit mode for instanced groups.
http://thebuildingcoder.typepad.com/blog/2011/11/editing-a-group-take-two.html
This article raises the same questions as the previous post. I can ungroup and regroup all fine, but then the groups become unassociative.
http://thebuildingcoder.typepad.com/blog/2012/07/view-of-newgroup-duplicated-elements.html
This article was a bummer, because I was thinking of a work around where I could do this:
1.) read the contents of each instance.
2.) if they are identical, but with a different location and orientation, save all locations and orientations of the instances of the group.
3.) Delete all but one group.
4.) ungroup the lone group.
5.) Modify the parameters.
6.) Regroup using the old name.
7.) Retranslate and reorient the new group to the locations of the other groups.
That way i could theoretically maintain the associativity of the group and even keep the old name, but I wasn't able to get this copying to work, as stated in the article. :(
So that's where I'm at. I'm going to keep pluggin away and see if I can find a solution. Thanks for you help.