Buffer Size - How low can you go

Question

I was wondering if you guys can exchange some information about your Buffer Size settings in Logic and how much milage you can get out of it.
I upgraded to the new 8-core 2.8GHz MacPro a few weeks a go and thought I would live in 32Sample Buffer Size dreamland until the software developers come out with the next CPU hungry beast. But it looks like that a lot of the current Software Instruments bring down the new Intel Macs already to their knees.
*This is my setup:*
MacPro 2.8GHz 8-core, 12GB RAM, OSX 10.5.3, Logic 8.02, Fireface 800
*This is my Problem:*
If I'm looking at one channel of i.e. Sculpture, then all the 8 cores don't do me any good, because Logic can use only 1 core per channel strip. The additional cores come into place when I'm playing
multiple tracks and Logic spread the CPU workload across those cores. So if I set the Buffer Size to the minimum of 32 Samples, then it comes down to one 2.8GHz processor and if he is powerful enough to process that one Software instrument without clicks and interruptions.
Sculpture:
Some of the patches are already so demanding that I reach the CPU limit when I play chords of four to eight notes with the 32 Sample Setting. If I add some "heavy" FX Plug-ins like amp modeling then I definitely reach the limit.
_Trilogy and Atmosphere Wrapper:_
Most of the time I have to increase the buffer size to 128 just to play a few notes. These "workaround wrapper plugins" are a plain joke from Spectrasonics and almost useless. There is plenty of discussion in various forums how they pizzzed off o lot of their customers with the way they handled their Intel transition regarding these two great plugins.
*Audio Interface Considerations:*
The different vendors of audio interfaces brag about their low latency of their devices. Especially Apogee's Symphony System was supposed to deliver extremely low latency. When they demoed their hardware at various Apple events, they played gazzillions of track and plug-ins and everything was running at 32 Buffer Size. I never saw however a demo where they loaded a gazzillions Sculpture instruments and showed that playing with 32 Buffer Size.
*Here are my basic three questions:*
1) Anybody experiencing already the same limitations with the new MacPros when it comes to intense Software Instruments
2) Anybody uses the 3.2GHz machines and has better results, or is it just marginal.
3) Anybody running the Symphony System and can throw any Software Instruments at it with 32 Buffer Size.
+BTW, the OSX 10.5.3 update fixed the constant popping up of the "System Overload" window, but regarding the CPU load with Software Instruments, I don't see that much of an improvement.+

Answer 1

My system is happy at 32 samples with the FF800... This is on the Jan 8 Core with 6 gig RAM, running X.5.3, Logic 8.0.2.
Plugs include - NI Komplete5 bundle, Waves GOLD, BFD2 (thought this would stump it but it's fine with 2.0.4) Access Virus TI Snow.
Safety IO buffer off and the Buffer set to small.