I continue to read about constant notifications about updates being available for the new versions of Pages 6, Keynote 6+, and Numbers 3+ (why Apple calls these version 5 is beyond me). I have not read or found a way to turn those off without affecting other notifications. However, I do not get "continuous" update nags, either. Here's how I have things set up:
1. Create a folder for both the new (crippled) Suite and one for the old (fully satisfactory) ones. This is important as the Software Updater will, I'm pretty sure, install the new updates in your Applications directory/folder. That just makes it too easy to accidentally open them, in my opinion. Be sure to use useful and easily recognizable names (The old one were called iWorks '04, the new ones are called iWorks '09, just following M$'s "lead" I guess 
).
2. Create three folders for all your current Pages, Keynote, and Numbers documents, inside the 'iWorks '04' directory (or whatever you named it).
3. Now, the hard part! Breaking old habits!Never double-click a file for any of file made with the old versions.
If you use Column View (in PathFinder, anyway), it's a simple matter of dragging a file to it's creator app, other Views and/or Finder may make this more difficult since you have very little control on where items will be in the window.
I have tried resetting the "Open with..." control in a file's Info window to the old version; Doesn't work.
I have tried setting my choice in DefaultAppX; Doesn't work for these documents probably because Apple dumped 'creator', and 'type' codes to assuage stupid Windows users.
I
do, still get Noticcfiuation Alerts about updates to the new apps, but they come only rarely, now, and the "Updates" counter normally indicates updates that may be important. When I do get a Notification of one of the new/crippled apps, I simply make the download and move the new apps to the 'out-of-the-way' folder, if they ended up in Applications. Apple may tell me how they want me to use their software, but that doesn't mean I have to... yet. It's probably good that I never told them that I used FileMaker Pro as a page layout app before Pages!!
I hope this helps a bit. It's not the "Apple Way", but that seems to be changing to "The Apple Way or the highway!"
