Finally I've found that my ZFS pool is not corrupted. Old server imports/exports pool without any problem. The only difference was in ZFS kernel version and modules versions:
Old: kernel 3.13.0-39-generic, SPL: v0.6.3-1~trusty, ZFS: v0.6.3-3~trusty
New: kernel 3.13.0-43-generic, SPL: v0.6.3-3~trusty, ZFS: v0.6.3-5~trusty
And, zfs slices were made in single partitions, starting from block 2048. So the RAID controller doesn't affect L0,L1 labels at all, just zeroed partition tables.
The only thing I've done to import - restored partition tables (zpool import still shows pool as FAULTY) and make the /dev/disk/myzfs dir and made symlinks to zpool members partitions devices similarly like /dev/disk/by-id have (attempt to "zpool import -d /dev/disk/by-id" shows pool as FAULTY).
"zpool import -d /dev/disk/myzfs" shows my pool as ONLINE and "zpool import -d /dev/disk/myzfs nas" have succeeded.
Unfortunately, I was unable to replicate the kernel-SPL-ZFS kernel and modules combination like on old server - have not found how to get the old ppa:zfs-native/stable packages. So, I couldn't tell if this is the module revision changes or whatever it could be.