I know Nigel Burkin uses code 55 Atlas on his layout and it does look good:
http://nigelburkin.wordpress.com/2010/04/
Both being code 55 I suppose it could all depend on how far up the profile the spikes come. My knowledge of 'N' is virtually non-existent, although I understand that fitting decoders can be a problem and that trucks are often swopped. I don't even know if you can get Kadee couplers for 'N'!
Having seen some very impressive US themed 'N' layouts recently,however,it is very enticing:
http://genevasub.blogspot.com/
http://csxdixieline.blogspot.com/
http://www.mrlmodeler.com/MRL_Modeler.html
http://www.scarthbridge.pwp.blueyonder.co.uk/index.html