Not much realworld experience, but I've dabbled with the demos on and off over the years. Generally, as with most 3rd-party plug-ins, performance of effects usually is better than what's built into AE. That can easily amount to several minutes rendering time saved per project and while working many things just feel snappier. That being said, the whole point would therefore be to change your workflows to use those plug-ins all the time in place of the AE ones. Personally I've never felt the need for BCC and much prefer GenArts Sapphire. I'm a graphically oriented person and most of what you can do in BCC you can just as well do elsewhere with more creative freedom, but of course it will cost you more money to buy all those extra plug-ins. To me BCC is more "editor porn", meaning it's very obvious that they sell those plug-ins for pretty much each and every editing suite and the AE version is just one branch. Some of the stuff is a bit too dumbed down and too straightforward for my taste. Of course if you do such stuff all the time for corporate video and need to be cost efficient, it can be just the ticket...
Thanks for the update.
This is the sort of thing I want to know you see - I have only had experience with After Effects itself, and all tutorials and basic study material (such as the books I have) give you great basics, and then it is up to you to use what you learn in creative and new ways. I still need to practice more to tart opening my mind to the posibilities. For me, the plug-ins would be "Quick-Fixes", but these come with the added danger of stopping me from thinking creatively for myself.
So.... Ill get a copy of the trial versions and use them to play around with the native tools to see what I can replictae. For our roject, we want quality over quantity, so if I need to spend more time to get an effect to look better, I would rather do that. I will also go and check out GenArts Sapphire now.