There is one legal problem with using a dual-band rig as a crossband repeater.
Both the 2-meter and 70-cm sides are ham transmitters, and must be ID'd every 10
minutes and at the end of every series of transmissions, just like every other
station and repeater. See this article:

How can I legally make my VHF/UHF station into a crossband repeater?
http://www.arrl.org/FandES/field/reg...l#_Toc70492016

Some people say "In an emergency, all rules are out the window, and anything
goes." Maybe, but I doubt it; I think ID rules still apply during emergencies.
But whenever you practice communication procedures (and you must practice to
make sure it will work in an emergency), all the rules apply.

73 de Dick, AC7EL

On 23 Feb 2007 16:34:15 -0500, Steve Bonine wrote:

As the time of year approaches to begin thinking about hurricanes and
disaster communications, I'm going to upgrade my 2-meter rig with one
that is capable of crossband repeat. I would like for this same radio
to double as my in-shack equipment during normal times.

I'm looking for something with enough power to handle marginal
conditions, rugged and able to handle high temperatures and long duty
cycles, and reasonably easy to operate in the field. (I don't mind
needing a computer and software to set up lots of memories, but I need
to be able to program in an unknown repeater in the field when the
computer isn't available.) Naturally the vendors assure me that all
their new gear can do this, but somehow I'd rather hear it from people
who have actually done it in the heat of battle.

73, Steve KB9X
73 de Dick, AC7EL