i have a xl1200c 2008 its beautiful. i think you should look into a used dyna there about the same price as a new 48 and it'll only be about a year old but bigger engine more comfterble for the wife.
harley is harley is harley.i liked my yamaha,i love my harley.
I'd say get whick ever one looks better to you. You can always buy a used fuel tank for a 2004-or later Custon 1200 and it would give you more range, 4.5 gallons vs. 2.2 or so with the stock 48. Realistically you loose a little capacity on both bikes because the fuel pump is in the tank. My Nightster owners manual lists the tank at 3.3 gallons but the most I've been able to squeeze in t here is lik 2.8 gallons. That was when I ran it completely out of gas one day. The bikes get about 40-50 miles to the gallon depending on how you ride so figure how often you want to stop for gas and a hotdog.