AFAIR, there are very very few real hardware differences between HP3K and
HP9K servers.

- 9x8s and Ex5s are identical, except for the MFIO (MultiFunction) board,
which autodetects whether it's AUI or BNC hooked on the 9K and has a switch
to select between AUI and BNC on the 3K, that need to be manually
repositioned.
- Same distinction for K-Class machines ... Autodetection on the 9K, manual
switch on the 3K. And the 9000 K-class has always supported HSC, and the 3K
does (did ?) not support it. Anyone from HP can please confirm the HSC
support status on the 3K ?
-AFAIK, T-class are identical, except that 12-way MP was supported much
earlier on HP-UX boxes than on MPE/iX. Don't ask me why ...
- Should we consider older boxes ? Novas (9x7 HP3ks and F/G/H/I 9ks) were
also quite similar, except that the 9ks had more I/O options. 3ks were LX
(2 slots) or RX (4 slots) or SX (12 slots).
- There is the NVM (non-volatile memory) reconfiguration that needs to be
done when installing a new board or converting a box. THE HP CE basically
off-line configures a few items, including a license allowing <x> MPE/iX
Users and/or <y> HP-UX users. Note that an HP-UX box can't boot MPE (why
the heck should it ?), BUT an MPE/iX box CAN boot HP-UX, due to the fact
that off-line diags (the HP Support Tape) in fact boot an HP-UX kernel.
AFAIR (but I'm no longer an HP employee), the NVM reconfiguration is done
with HP proprietary tools. That might be the point of conflict (I've not
yet read the article, sorry) : if anyone uses an HP proprietary tool (or
any other tool, for that matter) without having properly acquired the
licence or right-to-use or whatever, is this use legal or not ? IMVHO, it's
not, period.
- And, of course, there are the front label (who wants to have an HP3000
with an HP9000 label ?) and back label (Product numbers are not the same).

Just my Euro 0,02 (yes, I'm on the "other" side of the pond) ...

Christian Lheureux
Consultant for HP Systems and Facilities Management
APPIC R.H.
France
... and former HP employee, BTW

Please note that I wrote this mail on my own. Therefore, it merely
represents my opinions, neither my current employer's (APPIC R.H.) nor any
of my previous employers', including HP. Yes, yes, that's my idea of a
disclaimer !!!