When software isn't updated, issues will eventually show up.
As an example, I have no doubt that for a while in the past, SampleTron, SampleMoog and the other library/players - which haven't been updated since 2009, by the way - worked just fine under Mac OS.
As of (not so) recently however, some of us are experiencing an issue causing instrument loading time to increase exponentially for each new patch we audition, making the host irresponsive.
This could be due to anything - an update in some of the components of the OS itself or something like that. Since the plug-ins aren't updated, glitches and bugs crawl in...
The workaround would be to use SampleTank to load those samples. Which is already a compromise, but, hey...
Only problem is that, every time I've messed w/ IK instruments' sample directories, I've had to re-authorize every single instrument (on top of re-downloading the buggy authorization manager several times because it kept prompting me for an update randomly between authorizations).
Anyway, long story short, it took me forever. And I said - so long IK.
Now, if IK had only maintained its software and kept it up to date - not re-invent the whole thing w/ a new GUI and new features and whatsoever, but just made sure that their currently available products work correctly NOW, not 3 years ago, I personally couldn't care less how long it'd take them to develop ST 3.
They may never develop it for all I care.
Incidentally, all of my issues w/ ST and ST instruments are native 32 bit issue - I'm not yet using my host in 64 bits.