About two years ago I installed kubuntu on the all the users pcs where I work- about 11 boxes. Never had a virus or any sort of security problem with them. We deal with a lot of email based comms from the public, and the email addresses we have are published on the web. Specifically, we use okular to view PDFs. I'm not sure what vunrabilities it has, but we have never been the victim of any. I had to install Linux acrobat reader the other day to read someones cv(I think the fonts were missing in okular)! But other then that I have never needed it (and have since removed acrobat).
For creation we use open office built in PDF export, which works fine, other then for some reason, by default, it saves PDFs in presentation mode!
I guess it depends on what you need to do, for the vast majority of users, acrobat is overkill, all they want to do is read a doc, and copy text out of it. Any extra features which are uneeded are a vunrability or bloat, in my opinion.