Out of frying pan and into fire

If you're getting off a proprietary hardware platform like Z-series mainframe, why would you jump to another proprietary platform like HP_UX or AIX?

Perhaps you've just got used to spending large sums of money and it's too much of a step down from the addition to putting vendors' kids through college.

Especially if you're moving to Linux, my recommendation would be x86 platform.

There are some things that you cannot move, due to application portability, software vendor support, etc, but for the other 95%, get going: this is a purely financial argument and the days of this platform not being reliable enough are so 4 years ago.

Would anyone disagree - and have a pragmatic argument to the contrary?