Remember stacking has downsides too. When you adjust or apply metadata to a "closed" stack, it only applies to the image that's shown - not those hidden inside the stack. While in some circumstances that may be what you want, it can also be a pain in the backside (and is what led me to write my Syncomatic plugin). For example, you may only want a star rating to apply to the top image as you're using stacking to shortlist or show only the best pictures. But if they are merely bracketed, they may all be worth x stars. Or consider keywords, here you'd often want them to apply to all the images, but that does depend on what you are mentally using stacking to achieve. If you want it to indicate the others are rejects, stacking may be preliminary to deleting, so it doesn't matter if you don't keyword them. But you may be using stacking to de-clutter the catalogue's appearance, in which case it's an annoyance that you have to open stacks to apply metadata or adjust the images. It's an inherent awkwardness of stacking.
Also, stacking is a great way for you never to appreciate "slow burners" or forget certain variations existed. If they hadn't been hidden in a stack, might you have looked more closely at them and seen something you hadn't at first appreciated?
A couple of other details are worth noticing
- In LR4 the pick flags are now global, meaning you flag a picture in a collection and it'll be flagged everywhere. But now stacking has gone local and you can create stacks in collections.
- If you use LR4's new trick to drag a folder into the Collections panel, LR creates a new collection with any stacking copied from the folder.