Finally I've time to try it out. It works just fine, especially with kqemu – a kernel module for speedup.
I tried 3 systems till now: Windows XP 32bit, Netbsd 3.1 and Solaris 9. No problem with installing Solaris and Windows. The NetBSD dislikes kqemu module – it spits out a 'Warning: no /dev/console' and hangs when trying to boot installation iso. The (simple) solution is to add -no-kqemu to the qemu command-line (even for standard booting of installed system, otherwise it won't boot with no warning).
Going to test it all harder :). First thing I took a note is the processor load; it's low, at least I expected it to be more hardware exacring.