So, I thought, why aren't these new maps showing up? Compatibility?
Just opening the original maps and mod maps in wordpad, here's what seems different.
The initial header on the original maps is 'daeh' and then becomes ascii unreadable.
The initial header on the mod maps is 'daeha' and then becomes ascii unreadable.
The version (I think this is what it is, only other readable item in header) for the original maps is 01.00.00.0564.
The version for the mod maps is 01.00.00.0609.
The version for the Halo CE I am running is 01.00.05.0610
I'm hoping that my problem is actually something dumb like "you idiot, your mod maps go in the 'Mapsmod' directory", but I included the above just in case it matters.
Can you tell I've really got a couple of the mods I want to try?

Thanks for your help