To throw another wrinkle into this.... The IBM VTS is supported by zSeries as well, as Win/NT, Win/2000, AIX, Sun Solaris, HP-UX. I'm printing off the manuals now to see if the unit will support these environments, shared, at the same time. That would be a great solution.
AND There are new VTS units now. The TS7700 and the TS7510. If the B10 doesn't do what we want, these new units might. Tom Duerbusch THD Consulting