As for the passenger seat, according to Bike Solutions, you lose about 1" of butt space, but can sit up straighter. I'm 6'1", weigh about 235 and the passenger seat will hold me. If I were to remove the Utopia backrest, I'd gain another inch or two in the passenger area.
The extra foam does feel much better. Due to the cold weather, I have not been able to ride any long distances to give the seat a good test, but the short rides are good.
The extra 2" of driver space (with the large seat modification) is great for me. I have the Iso II pegs with the mini arms, allowing me to almost straighten my legs completely. If I were to take off my Show Chrome deflectors I could probably slip the pegs more forward and straighten my legs completely but I would lose the ability to deflect engine heat off my legs in hot weather.
Its a good thing I have long arms or the handlebar risers might have to be installed. John at Bike Solutions mentioned that I was "borderline" for the risers. Again, a long ride will help me decide about those, too.
I got my seat modified in just over a week, shipping from/to the east coast to/from Texas. Best advice I have is find someone in your area with the Wingsoft seat and ask to sit on it. Where are you located?