hi,
there is no problem: FAStT or a shared SCSI bus can
share the same partition to 2 or 3 and 4 hosts.
The problem is that before or after your systems will crash.
If you use NTFS it will appen before, with Fat32 after!
Have you never attached two keyboards to a machine ? Today using USB it is possible, and also 2 mouses; if you have 2 chairs, you can put also 2 persons to work with the same video: it works fine technically speaking, but I don't want know what is written in the same Word document;
try with two women: the result may be straightforward !
bye