Guys, calm down ! The G4 is long gone in terms of audio calculation power. It cannot handle todays requirements of really good algorithms - which means good sounding software.
The G5 in contrast is a very good processor, but it needs good compilers to bring out the power of it. Mateusz, go ahead with a G5 compatible Master Comp - I will buy it immediately ! At least if my Dual G5 1,8 Ghz can handle it ;-)