Re-installed system today, now using zfs-filesystem. I do not know is it just something I imagine or is it really faster than old UFS, certainly it feels faster. Adding partition reserved for PCBSD from usb-harddisk to common pool was surprisingly easy, only bad surprise was that system stubbornly refused to boot after that. Reason for that was that said HD started slowly so that system simply stopped to wait for it and could'nt mount filesystem, after booting to linux and little studying I could boot up PCBSD by using boot console and parameter set kern.cam.boot_delay=10000, after that system booted normally, added said parameter then to loader.conf.