I have always just used the Flat Pattern feature and put it into a family table. It hasn't given my any problems when I worked at places that had Pro/INTRALINK. We are not on Windchill yet; so, I have yet to experience the problems people are having with family tables. (People used to complain about it on Pro/I and Pro/PDM as well..) I have used Unbend / Bend Back if I want to get a feature that I have to create in the flat, but then I might create a Flat Pattern feature anyway. It's nice because it's always the last feature. This makes it nice for mapkeys.
Set Up / Flat State (BTW) is just a fancy way to create an Unbend with family table. It's like a PTC built in mapkey.
There was some talk about eliminating one or the other.
The simplified rep method is intriguing. I may try it one day, but I don't have a compelling reason to use it right now. I have seen it before on the forums.
You have to be careful about how you use Unbend / Bend Back, because you can create a mess with multiple UB/BB pairs. I would keep these pretty late in the model tree order as well in case of developing any unwanted parent-child relationships.
I evaluated Solid Edge for my company (2 jobs ago) and it's sheet metal package is pretty nice. The flat pattern is just a view option. There is no need to create a feature for it. This was almost 10 years ago. It would be nice if PTC would come up with something similar (assuming that the geometry could be flattened.) Both this and family table functionality needs a serious revision.