I received the new one, I had updated OSX in 10.6.7 and it is really better, I can use 8 layers at the the time with out any trouble (not yet tested in HD) using HD 7200 rpm. I will try later with medias on a SSD and SSD via thunderbolt.

I must use an other dis than the OS one even if it is a SSD. Catalyst and media on the same HD I have freezes.