There's no real performance advantage to the 1100XX shock. It's a tad longer at 320mm, so that would be nice. Besides that, you would need to upgrade the valving in the XX shock at minimum in order to see any improvement.
Since the 6th gens use a 315mm long shock you are kind of out of luck when it comes to options.
I put a blackbird shock on my 6th Gen and it's was pretty much the way Jamie describes it.
It was nice that it was a tad longer, and it was nice that the spring was a tad bit stiffer. Otherwise, it was the same POS crap shock that the OEM 6th Gen has.
I eventually upgraded to a full Elka shock, so I sold the shock to Silver788. He found that the shock was a nice improvement for his 5th Gen since the Blackbird shock with its stiffer spring supports his weight better than the stock VFR shock.