looking for ideas: triple booting and personal data

[Aryeh M. Friedman]

I am creating a triple boot machine (FB, Linux, Vista) and want to keep
all non-system files (i.e. any thing I made vs. was installed by the OS
[including 3rd party software]) avaible (r/w) by all three OS's.   I
know I can do this by putting /usr/home on a NTFS partition but am
worried about the slowness of ntfs-3g/ntfsprogs (90% of the time I am in
FreeBSD and have several things going that need decent disk performence
[bit torrents]).  Any ideas? 

BTW an added plus would be some way to automatically have one or all the
OS's maintain archival copies for backup purposes