ZFS - whole disk or partition or BSD slice?

[james]

I have a 9.1 system with some SATA disks in RAIDZ, upgraded from 9.0.

The disks are all the same type, and I formatted them for FreeBSD and 
put ZFS in a slice covering most of them.

I have seen suggestions for OpenIndiana etc that it is better to let ZFS 
have the whole raw disk and that this can control the way it manages the 
disk writeback mode.

Does this apply to FreeBSD and ZFS too?

Presumably the disks are currently FreeBSD-specific.  If I used raw 
disks instead of slices, could I read them from a Solaris system too?