[JonBike]

I have these tyres on my F800GT, but not the GT version of the tyres, just the standard sizes and standard version. I've had them on the bike for approx 2000-3000 miles now. I generally only ride when the weather is good, and my journeys are mostly for fun. The bike handles great with these tyres, I feel confident on the bike to lean over to the edge of the rear tyre. Handling and stability are great. I've also been caught out in the rain a few times, and I didn't really notice any difference in grip or handling, but when its wet, I take it easy anyway.
I would agree that this tyre is on the sporty side, and this suites me very well, as I don't do a lot of mileage, and when I'm out I like to have fun. I generally ride the bike on well surfaced country roads, out of town. So if you like enjoying good amounts of lean in the corners, you'll like these tyres. Powering through and out of corners is fine too, I've not noticed any issues doing this. I think the compound of the tyre on the edges is definitely softer than the middle, as my read tyre on the sides looks worn, but still has a good profile.
Braking, I've not had any problems too. I have progressive springs in the front forks, and dive is reduced considerably, so I can brake hard and late if I want to. Generally I don't brake so hard, but with the springs the bike doesn't rock when I release the brakes and tip the bike in. So I can extract yet more fun from the bike. Comfort hasn't noticably reduced with the springs either, but they are harder of course.
Anyway, if you are into sporty riding, enjoying lean in the corners, and nice neutral handling that gives you the confidence to be able to lean over to the edge, you'll like these tyres.