i do have pictures of my car on this site but they are in the topic post pics of your car. i think they are on the tenth page near the bottom. you can see that the ride was a little high, but that has since changed and there have been some mods to the rear lights (smoked lenses). hydroplaning has never been an issue. the bay area can get very wet and this year especially and i haven't had any issues. as for the ride around town. it is like any low profile tire. when you are on good roads the ride is fine. but on nasty roads, and we have a few, there are going to be more bumps than usual. for overall driving purposes though, the ride should be fine. the heav y steering is just the nature of having a wider tire (in my case 8" vs. 6.5"). but granted that you never crank the wheel all the way in one direction (enourmous strain on the power steering pump) then the steering setup in the mercedes will be able to handle it. if power steering pump is kinda weak, or you want to be careful, then you might want to look into a power steering pump from a 4matic model. they are bigger and able to handle more strain because they were also used for the 4 matic system. goodluck in your choice.
also, just to add, that you should keep the same overall diameter on your wheels and tires because otherwise the speedometer will need recalibration, so overall the wheels are the same diameter, just more of it is steel instead of black rubber. it gives an old car new life like you won't believe.