Migrating ZFS from 8.3 to 10.1

[javocado]

Hello,

I am planning to migrate (upgrade) my system from FreeBSD 8.3 RELEASE to
10.1 RELEASE (both amd64). My zfs pool exists on it's own physical
device(s) so my upgrade will consist of:

1. install FreeBSD 10.1 on boot device (in a temp system)
2. remove 8.3 boot device (from production system)
3. install new 10.1 boot device and boot up production system
4. re-mount zfs FS

My question is, what do I need to know about how this change will affect or
impact the zpool and datasets? Is there any chance zfs data could be lost
or destroyed? Might there be a performance loss due to version differences?
Is upgrading the zpool (once booted to 10.1) strongly advised? Any
downsides or dangers there?

Some other info worth considering (production system):

ZFS filesystem version 5
ZFS storage pool version 28

Thanks!