Another opinion. I was, incidently, the one with the red 550 at the Rally last year. "No, Sir, you can't park with the GT's. You have to park over there next to the Port-A-John's.":lol
Two very different cars. I think it is important to remember that 2001 was the last year the 550 was constructed. What Ford did, and they did it WELL!, was build a race car for the street. IMO, the Ford GT is not a Grand Touring car, for all the reasons we know. The 550 was designed to be a true GT car as well as one you could drive on the track. The Pro Drive folks had a lot of success with it. The 550 is not as fast as the GT in a straight line accelleration, but it is not a whole lot slower, even carrying an additional 650 pounds of weight. When I bought my 550 new in 2001, I had the Fiorano handling package included. I tracked the car extensively, and it was a lot of fun. Lots of understeer due to the front engine and weight, patience to let the car hookup after turning into corners before getting back on the gas, excellent balance with very little body roll etc. I have to disagree with the statement that a 575 will kick a 550's butt on the track. The only differences between the two cars are ~ 15 more horsepower in the 575 due to the 5.75 liter engine vs the 550's 5.5 liter engine, and the availability of the "paddle shifter" in the 575. I have had the pleasure of driving with several 575's which also had the Fiorano package on the track and things were pretty even.
The visibility in the 550 all around is much better than the GT. The steering feel/response is quite good in the 550, but I think it may be better in the GT. I have only had the GT on a track for 2 days, so my experience is limited vs the 550. The stock brakes in the GT are superb-BUT-I think this is one car which must be dead straight under heavy breaking. The weight and balance configuration of the GT lends itself to rapid oversteer if one is not careful. The 550, on the other hand, is more difficult to slide the rear end out.
There has been a lot said about Ferrari maintenance costs. My 550 has over 38,000 miles and has had all the required service work done. Normal 5000 interval service has run from $600 to $700. The exception was the 30,000 mile service which was $8200, primarily due to the timing belts being changed. An oil change for the 550 costs less than the oil change I had done at 2500 miles for the GT.
That being said, I find myself reaching for thr GT keys when the weather turns nice here in Virginia. The GT is simply one of the most beautiful cars, IMO, ever designed and built by an American automobile manufacturer. The Corvette Stingray starting in 1963 may be a close second. As nice as a Tubi on a 550 sounds when all 12 cyls are working hard, it is not the same as that supercharger bellowing behind your head when you nail it, the "now I will push you back in the seat and hold you there until you let up" feel, the beauty of the car[midnight blue] in a lighted parking lot at night........ Yup, it's a Ford and not a Ferrari-but what a Ford!!!:thumbsup