[FT] Hardened Systems

With some of the discussion on fighter bays and launch tubes and the
separate systems balancing their flexibility due to the increased chance
of
a threshold taking out a system, I wondered if anyone had house rules on
Hardened Systems or System Armour?

Off the top of my head, for a 50% increase in cost and mass, a system
would
get a -1 modifier to all threshold rolls (same level as core systems in
the
FTFB).	Also needle attacks would only damage the system, not destroy
it.
Maybe draw a circle around the system icon to show it is hardened or
armored.

Those of you who loose fire cons too fast could harden one and it may
stay
around longer.	Carriers using the modular hanger/bay rules could harden
the
launch/recovery bay to keep them around as long as possible.  Lots of
possibilities.

Is the 50% increase about right or too much since 2 hardened systems
cost
and mass the same as 3 systems?  What do you think?

Dean