I have cross climates plus fitted to a 2012 jazz. When new the steering felt odd, but after a 1000 or so miles , ok. The plus points. Potholes are absorbed better. Wet braking is superb. Road holding very good. Not noticed any change in MPG. The big minus is that the tyres are only available with a load rating of 88 on the 15 inch rims. The standard tyres have a load rating of 84. The result is a tyre designed for a much heavier car is not as compliant, and you feel every imperfection in road surfaces. But come any snow, I think these tyres will get me home, compared to summer tyres. I see that Continental now make an all season tyre for the 15 inch jazz rims with the correct load rating of 84 now, so maybe a better bet for ride quality. Who knows !
Apparently Michelin uses exactly the same construction for all speed ratings and locad indexes - it's their 'geobox' concept. Whether that means everyone gets harsher ride, I'm not sure - but I put Cross Climates on daughters Golf and ride seemed absolutely fine, although it had Bridgestones on before and they're noted for having stiff sidewalls. Bear in mind XL tyres only carry heavier load at very high pressures - for any normal pressure they're actually slightly lower load than non-XL tyres.
I didn't monitor tyre wear on the Golf in great detail - they were on a couple of years so did 20K and still looked fine when the car was written off by an Argos van.
On our Jazzs we run the older one year round with 15" wheels and full winter Michelin Alpins, and the other with 16" Michelin Energy. Wear rate on the Winters is very similar to the summer.
I will say we drove the older one through the severe (by UK standards) winters of 2009/10 and 10/11 on its original 16" Dunlop SP2030's and it never gave a moments concern. But they are noted for being very soft tyres and they didn't last long.
I only ever drove the Jazz briefly on winters in snow once - I very nearly came a cropper by the lack of lateral grip on a tight bend. Wife now has a Tiguan with 4Motion and full winter tyres and I drove that across country on a snowy day in January - it would start and stop almost as normal, so it would be really easy to get carried away. Again, cornering required care that seemed out of proportion with the tyres other capabilities.