Since purchasing X3 last week I've browsed the forum here and noticed that some folks have suggested that the use of 32 bit plugins could be the cause of certain types of buggy behavior. Isn't bitbridge supposed to enable their use in X3? Or is there something I am missing?

It is supposed to do that.
Sometimes it does not work.
Welcome to the real world.

Sometimes Jbridge works when Bitbridge does not.
http://jstuff.wordpress.com/jbridge/.

For the sake of stability I only use 64 bit plugs as a rule.

Thanks all. Yes, I've used Jbridge in Studio One without any problems. And I do realize we're in the real world. At the end of the day, there are only a handful of 32 bit-only plugs I like using -- mainly, the FX plugs from Variety of Sound (aka Bootsy), and piano VSTi called Pianissimo -- which in a pinch I can live without. I'm just trying to determine whether with X3, it's merely a case of these not working, or rather, whether they cause larger problems, e.g. stability etc.

Some 32-bit plugins work just fine in 64-bit Sonar, and some do not.
 
Many folks have gone through the exercise of switching completely over to 64-bit plugin use, and many limit the continued use of 32-bit plugins to those that they test out to make sure they work properly with either BitBridge or JBridge.
 
Lots of plugin vendors have released free updates to include 64-bit versions of their plugins, so often it just involves looking to see if your 32-bit plugins have been released in a 64-bit version.
 
I used 32-bit versions of MinimogueVA and ARP2600VA for quite a while, but finally saw a great deal on a collection of synths from Arturia that included 64-bit versions of the Minimoog and ARP2600, so switched over to that collection, and am now exclusively using 64-bit plugins.
 
Bob Bone

I see your point, Bob, thanks. Again, it's just a matter of a few plugs which a) are good enough to bother with and b) have developers which for some reason just don't seem interested in creating 64 bit versions, which are my preference.  I guess I'll just try and see. Probably best to make a new version when I add one of the 32 bit plugs so that if it causes problems I can revert to the prior version, to avoid crippling the project.

What I did was to create a new sub-folder in my 32-bit VST plugins folder, and I would move ones that I found still worked properly in 64-bit Sonar into this new sub-folder.
 
I added the new sub-folder to the search path for 64-bit Sonar, to be the ONLY path to 32-bit plugins, and this works well for me, because I have retained a 32-bit X3 install, which has the parent folder (the 32-bit VST folder) - and the 32-bit Sonar will pick up the sub-folder and 'see' all the 32-bit plugins, while the 64-bit Sonar will only 'see' the 32-bit plugins that I moved into the sub-folder.
 
I hope that made sense, 
 
Bob Bone