that there may exist valid reasons in particular circumstances to
ignore a particular item, but the full implications must be
understood and carefully weighed before choosing a different
So their security concerns may or may not be addressed by individual reading systems. It's a good bet that the major ones will play ball, though--particularly as most of them have someone in the IDPF.
As far as downloading stuff from random places on the web--well, run a virus scan on anything you get and you'll probably be okay, but that's always riskier than going through "official" channels.