Well, I was looking at a bunch of options when I bough my wing in Nov. I considered a low mileage used 2002, a brand new 2004, and a new 2003. I ended up with a demo 2003. I got it for $14,500. It had 2200 miles on it, but it was sold as new. At that time, the 2004's were going for MSRP. If I was going to buy a 2004, I would have gone for one with ABS. That would have brought up the price to over $19 grand. At that time I was not totally sure how much commuting I would do on the bike. As it turns out, I ride in about 4 days a week. My 2003 was out of the vin range for the frame recall. I had the ECM done in January when I got my 4K service done.
As far as I can tell, the only major differences between the 2004 and 2003 is that the windshield and the lighted controls. Both of these are great things, but not enough to cough up the extra for it.
I guess if it came down to a difference of less then $1,000 I would go for the 04. In my case it worked out great.
Enjoy