The Virtual Disk setup is far out classed by anything IBM or SUN has to offer... Come to think of it, Linux LVM and EVMS are both equal to flexibility and command simplicity.
The only thing I like about HP-UX anymore is the ability to use nearly *ANYTHING* in the way of Programs and Utilities with TONS-O-COMPILE-TIME issues that can't be fixed easily. This is not a good enough reason to goto HP-UX but a good enough one to stay.
I haven't seen much in the way of conversions TO HPUX, although the Hardware *IS* still good (PA-RISC) though as Peter pointed out, it isn't as flexible in configurations/changes as IBM (Power4/5) and Sun (Sparc64) chassis/accessories/sub-systems etc...