Thanks for your interest, Hose!
The numbers from the NAMM-show are not valid for the final product, as the engine has undergone yet another optimization process in regard of RAM usage. Apart from that, all sets of Multi Impulse Responses differ a lot in size, depedant on the length of the reverb in the hall (up to 10 seconds), and the number of individual stage positions we recorded (between 25 and 40). - 12 GB of RAM seem to be a reasonable size, though, especially when using the Vienna Instruments's RAM Optimization feature.
CPU consumption, OTOH, relies mostly on the number of instruments actually playing on stage, the chosen output format, and the global latency settings. The i7 I used for the NAMM and Musikmesse presentations showed an average of 50 to 60 % of CPU-power for "Also sprach Zarathustra", with about 25 individual Vienna Instruments playing at the same time during the final chord - in 5-channel surround, at a latency of 2048 samples. The same piece should put less than half the load on the CPU in stereo. Very low latency settings will tax the CPU disproportionately high; we got reasonable results with 256 samples with the RME HDSP-audio system we used, but not with big arrangements.
... all these numbers may be subject to change without prior notice, of course! ;-)
HTH,