A GPS Question?

Hello all,

Short of looking through the docs of all the possible GPS' out there I
am hoping I can get a general, if not, specific answer to the following.

Do any of the handheld aviation GPS' have the capability to display
location in UTM, MGRS, and different datums such as NAD 27 or WGS84?

I suspect if they have that capability you'd be able to program
waypoints via the same systems.

Currently I am using a Garmin 12 XL which has and is serving me well. I
just program the lat/long of the surrounding airports or the ones I am
going to and viola. I can also use it while hiking or fishing. HOWEVER
(there is always a however) today I was out flying and wanted to go to
an airport I knew was close by but I did not have it programmed. This is
where the aviation GPS would have helped.

Thanks,
Fred