Ok, thanks for the advice.
I've been playing with a 0-coast for more than a year, and with STO+FORBIDDEN PLANET+MATHS+YARNS+DUAL ADSR since June, so I have quiet an idea of what I like and what I want - for example I really like Contour, reason why I want it in this rack. I also need powerful simple sounds for my work as a composer - STO is great for that part - and in another way I love random things, reason why I'm trying to have both in the same synth.
I spent time reading all the manuals - especially the one about 0-coast and the one about Maths.
Now I'd really like to go for a full system, but still I don't think I know all the modules enough to be totally sure that the systems works well...