Went with a 21in. DNA fatty spoke and left the 16incher in the rear. Like the look of the 16 out back with the 21. I can't tell a difference in the ride at all other than a lot of lookie loos!! Go for it!!
I work at Harley Davidson of Indianapolis and we have sold many sets of wheel packages with 21" and 18" wheels. All of my customers love the looks and the ride on their baggers. I have had customers ride all the way from Indiana to Colorado on their 21" wheels and say they didn't notice a difference. I personally have a 21" Coastal Moto wheel on my FL Softail and love the look and ride. You can't beat the look of a big wheel on the front FL.
Put the 21" up front and 18" in the rear. At first seemed that the quality of the ride went out the window. I now have lowered the front 1.5" and the ride has significantly improved.
All I can say is this. I rode an 09 street glide with 21/18 set up. And then I rode my 09 street glide stock. And I can tell you without a doubt there is definately loss of handling with the 21/18 set up. It was harder to hold your line and a noticeable wobble in the turns. Bare in mind I am from WV where we have very curvy roads. Im sure going straight down the road there wouldn't be much difference, but putting these two bikes hard in some turns, there was alot of difference. For this reason...I ordered 18/18 wheels for mine. Just my two cents.