Uses for change-type action?

[Stan Shebs <shebs at shebs dot cnchost dot com>]

Xconq's code has long included an action change-type that allows
a unit to change its type to a different type, while preserving
its other properties.  However, there seems never to have been a
game design that really needed it, and so the action has never
been used, and none of the interfaces provide a way to make a
unit do one.  Thus, the code is pretty much useless, and I'm
contemplating whacking it out.

However, I would hate to take it out only to add it back two
months from now, so I've been looking around to see if it has
any possible uses.  The most obvious use is for "unit upgrade",
where the player spends resources to make the unit into a more
desirable one.  time.g does something like this, though with a
combination of construction and garrisoning, so it doesn't
need a special action.  Upgrading seems to be an "optionless"
operation, in that there is only one choice of type for the
upgrade, which suggests replacing change-type with a simpler
action "upgrade" and making it player-accessible with a simple
command.

So my question is: are there any other uses for change-type?
I'm especially interested in uses in existing (commercial or
free) games, since I couldn't find any that actually gave the
player a choice of different types to change a unit into.

Stan