I own the G25 + Wheel StandPro. The only difference I'm aware of between G27/G25 WSP regarding the rest of the range is the top plate where the wheel itself and the gearshift lever will be fix to. The rest is the same.
As for the feedback, the more bulky part you show in the different pics (I belief the first would be from an older version of WSP) is the 2 longitudinal bars where the pedals will lie on - feedback, no matter how stronger it will be, will have no influence there.
I play constantly Supercar Challenge with max feedback force, which is at least twice as strong as the feedback was in the GT5TT and I have no problems with it. Stability is top notch and I'm a very pleased costumer of theirs and their aftersales service.