I agree, but the SHO and the WRX/STI are two entirely different cars. The Mazdaspeed 6 is a pretty sweet car, and I do have soft spot for Mazda, I've had several in the past and they were always great cars. I also believe that we should be pretty darn pleased that there is as much available as far as performance for the Ecoboost in the few years it has been available, and as you stated, it's going to get even better in the next few years. But I think the SHO/Flex/F-150 have proven themselves as winners, and it's hard to find fault with these vehicles on a whole, but if you are expecting the handling of a sports car, you may be disappointed. but overall the SHO is a great platform, handling isn't bad for the biggest car in Ford's stable, and over and over, I have heard/read that people are enjoying the comfort and room in the SHO over the Mustangs and the smaller cars. It really depends on what you want out of a vehicle...if you want only performance and nothing else, then the SHO isn't the car you want, there is faster, better handling vehicles out there, but I can't say the SHO has not disappointed me and although I still want a GT-500 I wouldn't want to give up my SHO to have one.
Just as a point of reference, I am able to keep up with BMW 7series and Saleen Mustangs without much problem in my tune only car.